Chapter 1: How Your Body Uses Light

Chapter Introduction

The sun is up somewhere right now.

The sky is turning from black to dark blue to pale gold somewhere on the Earth. Somewhere else the sky is gold turning to orange turning to pink turning to black. Light is moving across the planet, the way it always has, ever since the Earth started spinning. The Rooster has been watching this for a long, long time.

Hi. I am the Rooster.

We have met before.

If you read my G3 chapter — Light and Your Body — you already know a lot. You know your body has a clock inside it that follows the sun. You know morning light helps you wake up and feel ready for the day. You know evening dark helps your body get ready to sleep. You know the day-side belongs to the Rooster and the night-side belongs to the Cat — and the two of us are partners. You know the most important rule in the whole chapter: never look directly at the sun, ever. Not even for a second. Not even with regular sunglasses. Not during an eclipse without special certified glasses. You know that some kids who are blind or have low vision still have body clocks and follow rhythms in other ways. You know screens at night can make sleep harder.

Welcome back. The Rooster crows. I am happy you are here.

You are nine or ten years old now. You have lived through another year of mornings and evenings. You may have started noticing things about light that you did not notice before — how the light feels different in winter, how your body feels different on long summer days, how your phone or tablet feels at night compared to the same screen in the afternoon. You are ready for the next step.

This chapter has three big ideas, and each one builds one step beyond G3.

The first big idea is how your body actually uses light. At G3 I told you your body has a clock that follows the sun. At G4 I want to tell you something most kids your age do not know. Light has two jobs in your body. One job is helping you see — that one you already knew. The other job is setting your body's clock — and this job uses a special part of your eye that has nothing to do with seeing. We will look at this up close.

The second big idea is how to be ready for light. We will talk about morning light, afternoon outside time, evening wind-down, and night dark. We will talk about screens. We will talk about what to do in winter when daylight is short. The Cat (Coach Sleep) and I will keep working together — the Rooster handles the day, the Cat handles the night. We are still day-and-night partners.

The third big idea is the most important, as always. Light safety. The eye-safety rule has not changed since G3, and the Rooster is going to say it again because it matters that much. We will talk about eyes, screens, seasons, and feelings.

The Rooster is awake. Are you awake? Take one breath. Look at the brightest window in the room you are in right now. Notice the light. The Rooster is ready. Let us begin.

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Lesson 1.1: How Light Works in Your Body

Learning Objectives

By the end of this lesson, you will be able to:

• Name the two jobs that light does in your body
• Describe how your eyes use light to see
• Describe how your eyes use light to set your body's clock — a job most kids do not know about
• Tell why morning light is special for setting the clock
• Understand that kids with blindness or low vision still have a body clock that follows rhythms in other ways

Key Terms

The Rooster Watches Again

The Rooster has been watching the sky for a long, long time. At G3, I told you that your body has a clock that follows the sun. That is still true. The Rooster is not going to take it back. The Rooster is going to add to it.

Here is the new G4 idea. Light has two jobs in your body.

Job One: Light helps you see.

This one you already know. Light from the sun, or a lamp, or a screen, bounces off things — your hand, your book, your dog, this sentence — and enters your eyes. Your eyes turn the light into messages your brain understands. Your brain puts the messages together into the picture you see. All of this happens almost instantly, all day, every day [1].

Job Two: Light tells your body what time it is.

This one you almost certainly did not know. Your eye has a second job that has nothing to do with seeing. Inside your eye, at the back, there are special cells — the Rooster calls them clock cells — that do not help you see at all. They just sense how much light is around. When they sense bright light, they send a message deep into your brain: it is daytime. When they sense dimness, they send a different message: it is getting darker now. That message goes to your body's main clock — a tiny part of your brain that runs your body's timing — and your clock uses it to decide what your body should be doing right now [2].

That is why most kids do not know this exists. You cannot feel your clock cells working. You only feel the results — sleepy at night, alert in the morning, wanting to wind down as the evening light fades, naturally waking up when sunlight is coming through your window. All of that is your clock cells and your body's clock working together. Quietly. Constantly. For your whole life.

The Rooster thinks this is one of the most amazing things about being alive. There is a part of you that senses time of day without you even knowing it is happening.

Why Morning Light Is Special

Of all the light your body gets in a day, morning light is the strongest signal.

Why? A few reasons:

• Morning sunlight is brighter than indoor light. A sunny morning outside is hundreds of times brighter than a lamp inside. Your clock cells notice the difference.
• Morning light wakes up your clock for the day. Your body has been in low-light or no-light mode all night. When the clock cells suddenly sense bright outdoor light, your body's clock locks onto "this is when day starts" and times everything else around it.
• Morning light pushes the wind-down signal away until evening. When your clock gets a good strong morning signal, your body's natural sleepy chemistry stays low all day and only ramps up in the evening, the way it is supposed to [3, 4].

This is why kids who get a little morning light outside (or near a sunny window if they cannot go outside) often have an easier time falling asleep at night. The Cat (Coach Sleep) and I have been saying this since G3. We are saying it again. We will keep saying it.

The Rooster is not going to tell you exactly how many minutes of morning light to get, or how soon after waking up. That is grown-up territory and changes from kid to kid. At your age, the practice is simple: when you can, get a little outdoor light in the morning — even just on the walk to school, in the schoolyard before class, or while waiting for the bus. That is it. The Rooster has been doing this for thousands of years and finds it works pretty well.

People in many places, many cultures, many times in history have started their days outside, even before there were clocks or alarms. The morning light habit is one of the oldest human habits there is. It is not a special protocol. It is a normal human thing.

The Wake-Up Signal and the Wind-Down Signal

The Rooster wants you to remember two phrases. They are simple. They explain a lot.

The Wake-Up Signal. Bright light, especially morning sunlight, tells your body: it is day, be alert. Your body responds by making you feel more awake, more able to think, more ready to move. Your body's natural sleepy chemistry drops. Your alert-and-ready chemistry rises. Your body is on day-mode.

The Wind-Down Signal. As evening light fades, your eyes and clock cells sense the dimming. They send the message: it is getting late, slow down. Your body responds by slowly making the natural sleepy chemistry again. Your body's main clock starts preparing for sleep. Your body is getting ready for night-mode.

Both signals are running every day, automatically. You do not have to think about them. But they only work well when they get real signals — bright light during the day, dim light in the evening. When the signals get crossed (bright light at night, very little light all day), your body's clock gets confused and works less well [4, 5]. We will talk about this in Lesson 2.

Three Kinds of Light

At G3 I told you about three kinds of light. The Rooster brings them back now with a little more at G4:

1. Sunlight. The light from the sun. The strongest light on Earth. Sunlight is what your body's clock cells were built to read. A sunny day outside is much, much brighter than even the brightest indoor room — sometimes more than a hundred times brighter. Your clock cells love sunlight. Outdoors in the morning is the strongest wake-up signal there is.

2. Indoor light. Lamps, ceiling lights, kitchen lights, the lights in school. Most indoor lights are bright enough to see by but not very bright compared to outside. Your clock cells barely notice them during the day. (Sun outside is just so much brighter.) But here is the thing: at night, even indoor lights are way brighter than the moon and stars. Bright indoor lights at night can confuse your clock a little.

3. Screens. Phones, tablets, laptops, TVs, video game systems, e-readers with backlight. Screens are bright. They are designed to look right at your eyes. The kind of light they put out is bright and tricky — bright enough at night to send your clock cells a wake-up signal when your body should be getting a wind-down signal. The Cat and I have a lot to say about screens at night. We will say more in Lesson 2.

Kids With Different Light Pathways

The Rooster wants to make sure every kid feels included in this chapter, just like at G3.

Kids who are blind. Some kids do not see with their eyes the way other kids do. The Rooster respects this absolutely. Even kids who are totally blind may still have body clocks that respond to light in some way — through small amounts of light that reach the clock cells (which work a little separately from seeing for some people), or through time signals other than light. Your body uses meals, sleep times, sounds, temperatures, and routines from your family and school as clock signals too. Some blind people use very steady routines to keep their clocks on schedule. Trusted grown-ups, doctors, and the people who love you help with this. The Rooster's chapter still belongs to you.

Kids with low vision. Many kids see, but see differently — maybe they need glasses, maybe they have a condition that makes vision blurry or limits the field of view. Your eyes still have clock cells, and your body still responds to light cycles. Whatever you can see counts. Whatever you cannot see does not stop your body's clock from working.

Kids who are very light-sensitive. Some kids get migraines from bright light, or have eyes that hurt in strong sun. That is real. Tinted glasses, hats, shade, and trusted grown-up help all matter. Your body still wants the day-and-night signals. You may need to filter the light a bit. That is okay.

Kids who live in extreme places. Some kids live far north or far south, where summer can have nineteen-hour days and winter can have nineteen-hour nights. Some kids live near the equator, where every day is about the same length all year. Some kids live in places with months of heavy clouds. Your body's clock works wherever you are. It might just have to work a little harder to find a rhythm. Trusted grown-ups help with this too.

The Rooster sees you. All of you.

Lesson Check

1. What are the two jobs of light in your body?
2. What are clock cells, and where are they?
3. Why is morning light especially good at setting your body's clock?
4. What is the Wake-Up Signal? What is the Wind-Down Signal?
5. Why are screens called "bright and tricky light" in this chapter?

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Lesson 1.2: How to Be Ready for Light

Learning Objectives

By the end of this lesson, you will be able to:

• Describe a normal kid-friendly day in terms of light signals
• Explain why a little morning outside light helps both day energy and night sleep
• Name three habits that protect sleep at night involving screens and bright lights
• Describe how winter and summer change your body's light experience
• Talk with a trusted grown-up about light habits that fit your family

Key Terms

A Day in Light

Let me walk you through a normal day in terms of what your body's clock is doing. (Not every kid's day looks like this. The point is to show how the signals work.)

Early morning, just after waking. Your body's clock has been in low-light mode all night. Your sleepy chemistry has been doing its job. As you wake, your body starts the slow process of switching to day-mode. If you can open the curtains, look at a window, or even better, step outside (or look out a window if you cannot) — your clock cells get a strong wake-up signal. Your body's clock locks in: day has started. The Rooster crows. The Cat sleeps.

Morning, on the way to school. Outdoor light, even on a cloudy day, is much brighter than indoor light. The walk to school, the bus stop, the schoolyard — all of these give your clock cells more good signal. Your body's clock is happy.

Mid-day, school or activities. You are mostly indoors now. That is fine — your clock already got the morning signal. Your body is in day-mode all the way through.

Afternoon, recess or outdoor time. If you can get a little more outdoor light in the afternoon, your clock loves it. It does not have to be a long time. Even a short outdoor break helps your eyes too — kids who spend more outdoor time may have less trouble with their eyesight as they grow [6].

Late afternoon, after school. Sunlight is getting softer and lower. Indoor lights start to feel less harsh by comparison. Your body's day-mode is still going strong. Snack, homework, play, family.

Early evening, before dinner. Outside the sun is heading toward the horizon. Indoors the lights are still on. Your body has not started the wind-down yet, but it is coming.

Dinner time. Sunset somewhere around here, depending on the season. After the sun sets, the outdoor world is getting dim quickly. This is where your body's clock starts paying close attention to the lights inside.

After dinner, evening time. This is wind-down time. Your body wants the lights to start coming down with the world outside. Big bright lights at this point can confuse your clock. The Cat and the Rooster like soft, warmer light in this part of the day. Lamps. A book light. A quiet living room. (Not big bright overhead lights and not screens close to your face.)

An hour or so before bed. Your body is making the wind-down signal in full force now. Sleepy chemistry is rising. Screens — phones, tablets, TVs — can disrupt this. The Cat says it. The Rooster says it. The grown-ups in your life say it. Most kids your age do best with screens off at least half an hour before bed, and longer if you can.

Bedtime. Dark room. Calm body. The Rooster turns the day over to the Cat. The Cat takes it from here.

The Rooster does not expect every day to go exactly like this. Family schedules vary. Kids' homework, sports, after-school activities, family time, screen time, weekend mornings, holidays, sleep-overs — life has lots of patterns. The point is to understand the signals so you and your trusted grown-ups can build light habits that work for your family.

The Rooster-and-Cat Partnership Deepens

At G3 I told you the Rooster and the Cat are partners. The Cat handles the night, I handle the day. At G4 I want to be more specific about how we work together.

The Cat's chapter, How Sleep Works, talks about all the different phases your body goes through at night. Falling asleep. Deep sleep. Dream sleep. Light sleep before waking. The Cat knows the night part of your clock very well.

The Rooster handles the day part. Morning wake-up. Daytime alertness. Afternoon energy. Evening wind-down setup. The Cat and I together cover the whole twenty-four hours.

Here is the deepening at G4: the two halves of the clock work together. A good morning light signal makes the Cat's night work easier. Good sleep at night (the Cat's job) makes your body more ready to wake up clearly in the morning (the Rooster's job). They are two halves of one cycle. Mess up one, and the other gets harder. Take care of one, and the other improves.

The Cat and I are day-and-night partners. Best friends, the way only two coaches who never get to be on duty at the same time can be.

Screens at Night

The Rooster and the Cat both say this, and the Rooster will say it more directly at G4.

Screens at night confuse your body's clock.

Here is why. Screens are designed to grab your eyes' attention. The light they put out is bright enough that your clock cells read it as more day, not as wind-down. When you stare at a screen in the hour before bed, your body's wind-down signal gets weaker [4, 7]. Your sleepy chemistry rises more slowly. You may have a harder time falling asleep. You may sleep less well even after you do fall asleep.

Different kids handle this differently — some kids are very sensitive to screens at night, some less so. But on average, kids your age who use screens less close to bedtime fall asleep faster and sleep better. The Cat has the research.

Screen habits that help most kids:

• No screens in your bed. Beds are for sleeping (and sometimes for reading a paper book). Phones and tablets do not belong under the pillow.
• No screens for the half-hour before bed. Or longer if you can. The Rooster and the Cat like an hour even better.
• Dim screens in the evening. Most phones and tablets have a "night mode" or "warm light" setting your trusted grown-ups can help you set up. It is not a perfect fix, but it helps.
• No TV in the bedroom for going to sleep with. Falling asleep to a TV is harder on your clock than falling asleep in a quiet dim room.
• Bedroom dark for sleep. Curtains closed, big lights off, only a small night-light if you need it.

These are not rules the Rooster invented. Pediatricians, sleep researchers, and the American Academy of Pediatrics all support keeping screens away from bedtime at your age [4, 7]. The Cat has more in her chapter. The Rooster is just backing her up.

Winter and Summer

The Rooster wants to say something about seasons that is more developed at G4 than it was at G3.

Summer. Long days. Lots of daylight. Easy mornings. Sunset is late, sometimes really late. Your body's clock gets very strong wake-up signals all day. Some kids find it harder to fall asleep in summer because it is still light outside at bedtime — that is normal. Black-out curtains, a regular wind-down routine, and remembering that your body's clock still wants night-mode at the same time even if the sky is brighter can help.

Winter. Short days. Less daylight. Hard mornings. The sun rises later and sets earlier. Kids in northern places might leave for school before the sun is up and come home in the dark. This is harder for your body's clock. The wake-up signal is weaker because there is less morning light. The wind-down signal starts earlier because it gets dark sooner.

Some kids feel sleepier, slower, or sadder in winter. This is a real thing — not pretending, not being lazy. The body's clock is doing its best with less light to work with [8, 9]. Trusted grown-ups can help in a few ways:

• Get outside even briefly during midday when the sun is up (recess, lunch, a short walk)
• Open curtains in the morning even if it is gray outside
• Keep regular bedtime even when it gets dark early
• Keep regular wake-up time even when it is still dark
• Talk to a trusted grown-up if the sleepy or sad feeling is sticking around (this is the most important one)

For some kids, doctors might recommend a special bright lamp called a light box that gives off bright morning light indoors. Light boxes are real medical tools — they should only be used with a doctor's guidance, especially for kids. If a doctor has suggested one for you or someone in your family, they will explain how to use it. The Rooster does not prescribe light boxes — only doctors do that.

Vision-Different Kids and Light Habits

The Rooster brings this back from G3 because it still matters and there is more to say at G4.

If you are a kid who is blind, has low vision, or has a vision condition, your body's clock still works — sometimes through your eyes a little, sometimes through other rhythms (meal times, sleep schedule, sounds, temperature changes). Trusted grown-ups, doctors, and your family help you build rhythms that work for your body.

If you have a friend who is blind or has low vision:

• Their clock is real, just runs on different signals
• They may have routines that look unusual to you but are how their body keeps time
• They may need quieter, more predictable schedules — that is just what their body uses
• Never play with the assistive tools they use (canes, screen readers, talking watches) — those are tools that help them, not toys

The Rooster includes every kid in every chapter, no matter how their bodies work. That is part of being a good coach.

Practice With a Trusted Grown-Up

Like all the G4 coaches, the Rooster wants you to do one small thing while reading this chapter.

Find a trusted grown-up. Ask them: "What is one light habit we could try as a family for a week?"

Some ideas to discuss:

• Going outside together for five minutes in the morning before school
• Phones-off-and-away half an hour before bed
• Open the curtains every morning, even if it is gray out
• Dim the lights for the hour before bedtime
• One screen-free dinner during the week
• A short walk outside after dinner before it gets dark
• Opening the window in the morning to hear birds (the Rooster's favorite)

Pick one. Try it for a week. Talk about it after. The Rooster is rooting for you.

Lesson Check

1. Describe a normal day in terms of when your body's clock is getting wake-up signals and wind-down signals.
2. Why is morning outdoor light especially helpful even if it is only for a few minutes?
3. Why do screens at night confuse the body's clock?
4. Name two things that help in winter when daylight is short.
5. What is the Rooster's day-and-night partnership with the Cat? How do the two of them work together?

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Lesson 1.3: Light Safety

Learning Objectives

By the end of this lesson, you will be able to:

• State the most important light-safety rule in this chapter (the Rooster will say it again)
• Explain why you never look directly at the sun
• Describe what is special about an eclipse and what you would need to view one safely
• Name three other light-safety rules (lasers, very bright lights, screens close to the eyes for hours)
• Recognize seasonal mood changes and know what to do if a feeling sticks around
• Know who to tell if something hurts in your eye

Key Terms

The Rooster Is Honest

At G3, the Rooster told you the most important rule in this whole chapter. The Rooster is going to say it again at G4, because it has not changed and it never will.

Never look directly at the sun. Ever.

Not in summer. Not in winter. Not at sunrise. Not at sunset. Not for a second. Not even on a hazy day. Not through regular sunglasses. Not through a window that "makes the sun look dimmer." Not through your fingers.

The Rooster is firm about this because the Rooster loves you and the Rooster has seen what happens when this rule is broken.

Why Looking At the Sun Is Dangerous

At G3 I gave you the basic rule. At G4 I want to give you a little more, because you are old enough.

Here is what happens. Your eye is built to gather light and focus it on a small part at the back called the retina (a grown-up word — say it like RET-na). Most of the time this works perfectly. Soft light goes in, your retina makes pictures, you see.

The sun is so much brighter than any other light on Earth that when you look directly at it — even briefly — your eye focuses all that intense light onto a tiny spot at the back. That spot can burn. Not feel-hot kind of burn, but tissue-damaging burn. The sun is bright enough to damage the back of your eye in seconds [10]. This injury is called solar retinopathy.

The really hard part: your eye does not have feelings the way your skin does. You will not feel pain while it is happening. You may not realize you are damaging your eye until later, when you notice a blurry spot or a dark spot in your vision that does not go away. By then, the damage may be permanent. Eye doctors cannot always fix solar retinopathy.

That is why the rule is never. Not "be careful with the sun." Not "just a glance is okay." Never.

The Rooster is firm because the Rooster loves you. The Rooster's whole job is to be the bird that watches the sun safely from the side, never staring at it. You watch the sun the way the Rooster does — never directly, always from the side, always with full understanding of how strong it is.

Eclipses Are Special

Most kids will see at least one solar eclipse during their childhood. The Rooster wants you to know about them.

An eclipse is when the moon passes between the sun and the Earth and blocks part of the sun's light. The sky gets dim. Birds get quiet. Some animals start to act like it is evening. It is one of the most amazing things you will ever see in your life — if you see it safely.

Here is the dangerous part: during an eclipse, the sun is partly blocked, so it does not feel as bright as usual. People are tempted to look at it. You still cannot look at it. The part of the sun that is still showing is still bright enough to burn your retina, even more dangerously sometimes because your eyes adjust to the lower brightness and the damage happens before you realize.

The only safe way for kids to look at an eclipse:

• Certified eclipse glasses that meet a special safety standard (the package will say "ISO 12312-2") [11]
• Or watching a projected image (a special pinhole projector your grown-ups can make or buy)
• Or watching on a screen / TV broadcast

What is NOT safe for an eclipse:

• Regular sunglasses. (Not safe. The Rooster repeats: not safe.)
• Cameras, phones, binoculars, or telescopes pointed at the sun without special solar filters (without proper filters, these focus the sun's light even more strongly than your bare eye and can cause damage in less than a second)
• A welding mask or smoked glass (these are old advice that turned out not to work)
• Looking through clouds or "just for a moment"

There is one special case during a total eclipse: at the exact moment when the moon completely covers the sun (called totality, and only happening in a narrow strip of the Earth), it is briefly safe to look at the sun without glasses. The total moment usually lasts only a couple of minutes. Before and after totality — and during a partial eclipse anywhere on Earth — you must use eclipse glasses or projection. Your trusted grown-ups will know if you are in the path of totality. If you are not sure, the safe answer is always: use the glasses or do not look.

The Rooster is saying all of this because eclipses are wonderful and because some kids each year hurt their eyes during an eclipse because someone gave them old or wrong advice. Now you know.

Lasers Are Dangerous Too

Lasers are everywhere. Pointers your friend brings to school, gag toys at parties, cheap "laser pets" you can buy in stores, fancy ones in concerts and shows. The Rooster has rules.

Laser rules:

• Never shine a laser into anyone's eyes. Not yours, not your friend's, not a pet's. Even cheap laser pointers can damage retinas. Lasers focus all their light into a tiny point, and that tiny point hits the back of the eye in a tiny dot of damage [12].
• Never play "tag" with a laser pointer. Aiming at someone's face is dangerous.
• Never shine a laser at a moving vehicle. This is dangerous (and in many places illegal).
• Never shine a laser at planes. This is very serious (and illegal in the United States).
• If you have a laser pointer, treat it like a flashlight — point it at the floor or the wall when you are not using it. Better: leave laser pointers to grown-ups.

Other Bright-Light Safety

A few more notes from the Rooster:

• Welding light. If you ever see someone welding (sparks and very bright light from a torch), do not look at the bright spot. Welding light can burn eyes the same way the sun can. Trusted grown-ups handle welding.
• Very bright work lights and shop lights. Some kinds are bright enough to be hard on eyes if you stare for a long time. If a grown-up is using something like that, look away, do other things.
• Fireworks. Beautiful at a safe distance. Never stand close. Never touch a firework. Burns and eye injuries from fireworks send a lot of kids to the emergency room every year.
• Strong reflections. Bright sun off snow, white sand, water, or a car windshield can be intense. Sunglasses help. If your eyes are squinting hard, listen to them.

Screens Close to Eyes for Hours

This is not an eye-damage emergency the way the sun is, but the Rooster still wants to say something.

When your eyes spend hours and hours staring at something close (a tablet, a phone, a video game, a book), the muscles inside your eyes work hard. Your eyes can get tired, dry, or strained. Doing this for many hours every day, every week, year after year, may make your eyes more likely to develop nearsightedness (a condition where things far away look blurry) [13].

What helps:

• Take a break every twenty minutes or so. Look up. Look at something far away — a tree out the window, the far side of the room. Just for a few seconds. (Some eye doctors call this the twenty-twenty rule.)
• Spend outdoor time every day. Kids who spend more time outside in childhood may have a lower chance of developing nearsightedness. Outside, your eyes look at far things naturally. Plus you get all the light-clock benefits the Rooster has been telling you about.
• Hold screens at a normal arm's distance, not pressed against your face.
• Have your eyes checked. Trusted grown-ups schedule vision check-ups. If reading or seeing the board at school is hard, tell a grown-up.

When Eyes Hurt

If your eye ever:

• Has something in it that you cannot blink out (eyelash, sand, dust, an actual object)
• Was hit by something
• Was splashed with a chemical (cleaner, soap, paint)
• Suddenly hurts or burns for no reason
• Has a sudden blurry spot, dark spot, or weird vision change
• Has flashes of light that should not be there
• Has redness that does not go away

Tell a trusted grown-up right away. Right then. Not later.

For chemical splashes in the eye, the trusted grown-up will usually rinse the eye with clean water for several minutes. Eye chemicals are serious. If something splashes in your eye, even if you do not feel pain at first, tell an adult right away. Your eye is precious.

If a grown-up thinks the eye injury is serious, they may call 911 or take you straight to a doctor. 911 is the phone number grown-ups call for an emergency in the United States. Same number, same rule as in every other coach's chapter [14]. You tell a grown-up first. The grown-up makes the call. Eye injuries from chemicals, from being hit, or from puncture wounds are emergencies. The grown-ups will know what to do.

Seasonal Mood

The Rooster mentioned this at G3 and at the start of Lesson 2. The Rooster wants to say more at G4 because some of you are reaching an age where this will matter to know about.

Some kids feel different in winter than in summer. When days are short, when sunlight is rare, when it is cold and gray for weeks at a time, some kids feel sleepier, slower, sadder, less interested in things they usually like, more like staying inside under a blanket. This is real. It is not laziness. It is not pretending. The Rooster takes it seriously [8, 9].

This pattern has different names in different families. Some doctors call the more serious form seasonal affective disorder (or just SAD). Many people just call it the winter blues, or winter heaviness, or that time of year.

What you can do, in order of importance:

1. Tell a trusted grown-up. This is the most important step. If you notice you are feeling sadder or more tired across many days or weeks in winter, tell a parent or other caring adult. The grown-up will not be mad. They will probably be glad you told them.
2. Try to get outdoor light at midday. Even a few minutes. Even on cloudy days. Outdoor light at midday in winter is still much brighter than indoor light.
3. Keep your bedtime regular. Even if it gets dark at four in the afternoon. Same wake-up time too.
4. Move your body. The Lion would say the same. Movement helps mood in every season.
5. Stay connected. Spend time with people who care about you. Even when staying under the blanket feels easier.
6. If feelings are big or sticky, the grown-up will help you talk to a doctor or counselor. Some kids and grown-ups use a special bright light box, with a doctor's guidance. Some kids and grown-ups talk with a therapist. Some make small changes that help a lot. Whatever fits you and your family. The grown-ups know.

If feelings get really big — if you ever feel like you do not want to be here, or you want to hurt yourself — that is a serious feeling and you tell a grown-up RIGHT AWAY. Not later. Right then. The Rooster, the Turtle, and every other coach is saying the same thing. Crisis-resources section below.

Feelings About Light

The Rooster, like every other coach, makes room for feelings.

Some feelings about light you might have:

• Frustrated when winter mornings are dark and you have to get up anyway
• Worried about going outside in the sun (sunburn, sunscreen, hats)
• Anxious about screen time being limited
• Sad in winter, or in long stretches of gray weather
• Excited by long summer days, sometimes too excited to sleep
• Worried about eye health
• Sad if a family member has trouble seeing
• Curious about eclipses, lasers, fireworks
• Confused about all the screen rules
• Other feelings the Rooster has not named

All of these are normal. The Turtle's eighteen-feeling roster from G3 still holds. The Rooster adds: tell a trusted grown-up about the ones that get big or stay. The same trusted grown-ups who help with everything else can help with light feelings too.

You can start small:

• "Winter has been making me feel really tired. Can we talk about it?"
• "My eyes hurt at school sometimes. Can I see the eye doctor?"
• "My friend said I shouldn't worry about sunscreen, but the Rooster said I should. Which is right?"
• "Is it true that eclipse glasses are different from regular sunglasses?"
• "I had a weird dark spot in my eye after camping. Should I tell someone?"

Any of those is a great start.

When a Feeling Feels Really Scary or Unsafe

The Rooster, like the Bear, the Turtle, the Cat, the Lion, the Penguin, the Camel, and the Dolphin, is careful and clear here, because this part matters most.

Sometimes a feeling gets really big. Maybe a feeling about winter, about your eyes, about your body, or about something happening in your life makes you really scared. Maybe a feeling makes you want to hurt yourself. Maybe a feeling makes you not want to be here.

If a feeling like that ever comes up — at any time, in any season, about any topic — tell a trusted grown-up right away. Not later. Right then. The grown-up will not be mad. The grown-up will be glad you told them.

There are special phone numbers grown-ups can use when feelings get really scary or unsafe. You do not have to memorize the numbers. The grown-ups in your life can use them.

For an eye emergency or any other emergency where someone needs help right away:

• A grown-up can call 911. Real people answer fast and send help. Kids your age tell a grown-up first; the grown-up makes the call.

Helpers grown-ups can call when feelings feel really scary or unsafe:

• The 988 Suicide and Crisis Lifeline. A grown-up can call or text 988, day or night. Real people answer. They help right away.
• The Crisis Text Line. A grown-up can text the word HOME to 741741, day or night. Real people answer by text.

Helpers grown-ups can call about other big or hard worries:

• The SAMHSA National Helpline, which is 1-800-662-4357. Day or night.

For grown-ups concerned about a kid's eating or body image:

• The National Alliance for Eating Disorders at 866-662-1235, weekdays 9 to 7 Eastern.

These helpers are for grown-ups to use when you and they need them. Kids your age do not call helplines on your own. You tell a trusted grown-up first. The grown-up takes care of the rest.

The Bear, the Turtle, the Cat, the Lion, the Penguin, the Camel, the Dolphin, and the Rooster are all on the same team. We agree. We point to the same place. You are not alone.

The Rooster's Last Thought

Before we end this chapter, the Rooster wants to give you one last thought.

Light is the oldest thing.

The sun was here before the Earth was. The Earth started spinning a long, long time ago, and ever since, light has been moving across the planet in a circle, every day, without ever stopping. Your great-great-great grandparents lived under the same sun. Your great-great-great grandchildren will live under it too. Every animal that has ever lived — every bird, every fish, every Camel, every Penguin, every Bear, every Lion, every Turtle, every Cat, every Dolphin, every Rooster, every human — has lived inside this same rhythm of light and dark.

You are part of this rhythm. Your body is built for it. Your clock cells are built for it. Your wake-up signal and your wind-down signal have been working for you every day of your life without you ever knowing about them — until today.

Take care of your eyes. They are how you see this rhythm. They are also how your body's clock listens to it.

The Rooster crows. The Cat sleeps. The day continues. The Rooster will see you again.

Lesson Check

1. What is the most important light-safety rule in this whole chapter?
2. What is solar retinopathy, and why is it serious?
3. What is the only safe way for a kid to look at an eclipse (when not in the path of totality)?
4. Name two laser rules.
5. What should you do if you or a friend ever has an eye injury or something splashed in your eye? Who calls 911 if it is serious?
6. Name two things that help if you feel sadder in winter.

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End-of-Chapter Activity: A Week of Light Noticing

The Rooster has a noticing project for you. This is meant to be done over seven days — one whole week — with a trusted grown-up checking in with you.

What you need

• A small notebook or piece of paper
• A pencil
• A regular bedtime to keep
• A trusted grown-up to check in with you each day

What to do

Each day for seven days, you will notice two things about light and write them down. Just one sentence each.

Morning note: What light did you see first this morning? (Window? Lamp? Sky outside the bus? Phone screen?)

Evening note: What was the light like an hour before bed? (Bright lights? Dim lamps? Screens? Outside?)

That is the whole project. Two sentences a day. Seven days.

After seven days

Look at your fourteen sentences. What do you notice?

• Did most mornings start the same way? Or were they different on weekends?
• What kinds of light were on in the evening? Was it the same on school nights and on weekend nights?
• Was there one day where the morning light or evening light was unusual? What did your body feel like that day?

Talk with your grown-up. Pick one light habit your family wants to try for the next week — just one. Some ideas:

• Open the curtains together as soon as everyone is up
• Walk outside for five minutes after breakfast (or before school)
• Phones off the dinner table
• Dim the living room lights an hour before bedtime
• Screens off thirty minutes before bed
• Same wake-up time on weekends as on school days (a hard one — but the body's clock loves it)
• One outdoor activity on Saturday or Sunday

The Rooster does not expect perfection. The Rooster believes in noticing first, then building habits. The Rooster is proud of you for doing the noticing.

Optional extra

If you and your family want to, keep the light-noticing notebook going for a whole month. The Rooster will be very happy.

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Vocabulary Review

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Chapter Review

1. The Rooster says light has two jobs in your body. What are they?
2. What are clock cells? What do they do?
3. Why is morning light especially important for the body's clock?
4. What are the Wake-Up Signal and the Wind-Down Signal?
5. Why do screens at night confuse the body's clock?
6. Describe the Rooster-and-Cat day-and-night partnership.
7. What is the single most important safety rule in this entire chapter?
8. What is solar retinopathy, and why is it permanent?
9. During an eclipse, what is the only safe way for kids to look at the sun (when not in the path of totality)? What is NOT safe?
10. Name three laser rules.
11. Name two ways winter can affect how kids feel, and two things that help.
12. If your eye is injured or something is splashed in it, what do you do?
13. What do the Rooster and the other seven coaches have in common about feelings and trusted grown-ups?
14. What is the Rooster's "last thought" about the place of light in your life?

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Instructor's Guide

Pacing recommendations

This G4 Light chapter is the eighth G4 chapter in the Coach Light (Rooster) spiral and the second chapter of the Rooster's K-12 arc, building directly on G3 Light (Light and Your Body). Three lessons span seven to nine class periods at age-appropriate pace. The week of light noticing activity adds seven days of brief noticing-and-recording at home with family check-ins.

• Lesson 1.1 (How Light Works in Your Body): two to three class periods. The two jobs of light framing (seeing + body clock) is the structural-simplification deepening at G4. The clock-cells concept is age-appropriate and accurate without naming ipRGCs technically — kids should grasp that there is a non-seeing pathway in their eyes.
• Lesson 1.2 (How to Be Ready for Light): two to three class periods. Practice and habit-building lesson. Coordinate with families through the parent newsletter. The morning-light habit is framed as a general human practice across cultures, not as a branded protocol; the chapter explicitly does not prescribe lux values, minutes, or post-waking windows.
• Lesson 1.3 (Light Safety): three class periods. The eye-safety teaching — particularly the never-look-at-the-sun rule and the eclipse-safety content — is the most important safety material in the chapter and should be presented with the same gravity as G3 Water's drowning prevention, G4 Hot's hot-car safety, and G4 Breath's breath-hold-water safety.

Lesson check answers

Lesson 1.1

1. Job 1: Light helps you see. Job 2: Light tells your body what time of day it is (sets the body clock).
2. Clock cells are special cells at the back of the eye that sense how much light is around and send the message to the body's main clock in the brain. They do not help with seeing.
3. Morning sunlight is much brighter than indoor light and locks the body's clock onto when day starts. It also keeps the natural sleepy chemistry low during the day so it can rise properly in the evening.
4. Wake-Up Signal: bright morning light tells the body it is day, be alert. Wind-Down Signal: evening dimness tells the body it is getting late, slow down for sleep.
5. Screens are bright enough to confuse the clock cells into reading them as daytime even at night, which weakens the wind-down signal.

Lesson 1.2

1. Open-ended; teacher checks for accurate use of the two signals across the day arc.
2. A few minutes of morning outdoor light sets the body's clock for the day, which makes the wind-down at night happen on time and helps sleep.
3. Screens send bright wake-up-signal-like light to the clock cells in the evening, when the body should be making the wind-down signal.
4. Sample answers: outdoor light at midday (recess, lunch walk); regular bedtime even when it gets dark early; regular wake-up time even when it is still dark; movement; staying connected; talking to a trusted grown-up; a doctor-guided light box.
5. The Rooster handles the day half of the clock and the Cat handles the night half. Same clock — they cover the whole twenty-four hours together.

Lesson 1.3

1. Never look directly at the sun. Ever.
2. Solar retinopathy is an eye injury caused by sunlight focused on the back of the eye. It can be permanent because the burned spot may not heal, and you may not feel it happening.
3. Only safe way (outside the path of totality): certified eclipse glasses meeting ISO 12312-2, or a pinhole projection, or watching on a screen. Regular sunglasses, cameras / phones / binoculars / telescopes without solar filters, welding masks, and smoked glass are NOT safe.
4. Sample two: never shine a laser in anyone's eyes; never aim at people, animals, vehicles, or planes; treat them like flashlights, point at floor or wall when not in use; leave laser pointers to grown-ups.
5. Tell a trusted grown-up right away. For chemicals, rinse with clean water. For serious injuries (chemicals, punctures, being hit), grown-ups may call 911 or go straight to a doctor.
6. Sample two: outdoor light at midday; regular bedtime; movement; staying connected; talk to a trusted grown-up about ongoing feelings.

Chapter review answer key

1. Seeing, and setting the body's clock.
2. Special cells at the back of the eye that sense how much light is around and send time-of-day signals to the body's main clock in the brain. They do not contribute to vision.
3. Morning outdoor light is much brighter than indoor light, locks in the body's clock for the day, and keeps the body's natural sleepy chemistry low during the day so it can rise properly at night.
4. Wake-Up Signal: bright light tells the body it is day. Wind-Down Signal: dimming light tells the body it is getting toward night.
5. Screens are bright enough to be read by clock cells as wake-up signal light even at night, which delays the wind-down.
6. Same body clock, two halves. Rooster handles day. Cat handles night. Each one's work makes the other's easier.
7. Never look directly at the sun. Ever.
8. Solar retinopathy is permanent retinal damage from looking at the sun. The retina does not always heal from this kind of burn, and the damage may be irreversible.
9. Only safe: certified eclipse glasses with ISO 12312-2 rating, pinhole projection, or watching a TV broadcast. NOT safe: regular sunglasses, optical devices without solar filters, welding masks, smoked glass, looking through clouds, looking "just for a moment."
10. Sample three: never shine in anyone's eyes; never aim at vehicles or planes; treat them like flashlights when not in use; leave lasers to grown-ups; never play tag with a laser.
11. Sample: kids may feel sleepier, slower, sadder; daylight is shorter; mornings are dark; wind-down starts earlier. What helps: outdoor light at midday, regular sleep schedule, movement, staying connected, talking to a trusted grown-up.
12. Tell a trusted grown-up right away. For chemical splashes, the grown-up rinses the eye with clean water. For serious injuries, grown-ups call 911 or take you to a doctor.
13. All coaches agree: all feelings are okay, ongoing big feelings should be told to a trusted grown-up, the trusted grown-ups can use crisis-resource numbers if needed.
14. Light is the oldest rhythm. Every living thing has lived inside it. Your body is built for it. Your clock cells listen to it. Take care of your eyes — they are how you both see this rhythm and how your body's clock keeps time.

Discussion prompts

1. What was new in this chapter that you did not know before?
2. Why do you think most people have never heard of clock cells?
3. Why do the Rooster and the Cat call themselves "day-and-night partners"? How does that compare to the Penguin and the Camel calling themselves "climate twins"?
4. Eye safety: have you ever heard of someone hurting their eyes by looking at the sun or at lasers? (Held sensitively.) What did the Rooster say to do if you see this happening?
5. The Rooster does not give a "10 minutes of morning sunlight" rule. Why do you think the chapter avoids specific numbers?
6. What is one light habit you and your family could try?
7. Do you ever notice your mood changing with the seasons? What helps?
8. If you knew a friend who had been looking at lasers with their friends, what would you say to them?

Common student questions

1. "How long should I be outside in the morning?" — The Rooster does not give a specific time. A few minutes helps. More is better up to a point. There is no exact "right" number for your age. Trusted grown-ups decide what fits your family.
2. "Is the sun bad?" — No. The sun is wonderful. The sun is the most important light on Earth and your body needs it. The rule is never look directly at it. Look around in sunlight, play in sunlight, walk in sunlight — just never stare at the sun itself.
3. "What about cloudy days?" — Cloudy daylight is still much brighter than indoor light. Your clock cells still get a good signal. The Rooster likes cloudy mornings too.
4. "Is screen time bad?" — Screens are not bad in themselves. They are bright tricky light that can confuse your clock at night and can be hard on eyes for long stretches. Trusted grown-ups set screen rules for your family.
5. "What about Andrew Huberman / morning sunlight protocol / lux measurements?" — Some grown-ups follow specific protocols around morning light. Those protocols are designed for adults and require specific instruction. They are not appropriate prescriptions for kids your age. The chapter teaches morning light as a general human practice without specific counts — what humans have been doing for thousands of years.
6. "Can I look at the sun during sunrise or sunset? It looks dimmer." — No. Even when the sun looks dimmer because it is low on the horizon, the rule is never directly. Look around the sky, look at colors in the clouds, look at the light on things — never directly at the sun itself.
7. "What if I accidentally looked at the sun for a second?" — One accidental glance probably is not going to cause damage, but if you have any unusual vision changes after (a spot, a blur), tell a trusted grown-up. The Rooster wants you to avoid the habit of glancing at the sun — and to never do it on purpose.
8. "Can I use a phone in bed if it is on night mode?" — Night mode helps, but it is not a magic fix. The screen is still bright enough to affect your clock and to keep your brain engaged when your body wants to wind down. Phones in bed do not help sleep, even with night mode.

Parent communication template

Dear families,

This week we are reading Chapter 1 of the Grade 4 Coach Light (Rooster) chapter — How Your Body Uses Light. This is the second chapter in the Rooster's spiral (the first was in Grade 3) and the eighth chapter in the Grade 4 Library cycle.

The chapter teaches three big ideas: how light works in the body (two jobs — seeing and body clock; the special clock cells most kids do not know they have; the Wake-Up Signal and Wind-Down Signal); how to be ready for light (the day arc, screen habits, winter and summer differences, family light habits); and light safety (eye safety load-bearing, eclipse safety, lasers, screens for hours, seasonal mood, crisis resources).

The most important safety message in this chapter is the eye-safety rule: never look directly at the sun, ever. The chapter teaches this with the same gravity that other coaches' chapters teach their most important rules. We will spend real classroom time on solar retinopathy and on eclipse safety (only ISO 12312-2-certified eclipse glasses, never regular sunglasses, optical devices without filters, or smoked glass). Please reinforce this rule at home — especially around expected solar eclipses in the coming years.

We will also be doing a week of light noticing — kids will write one sentence each morning and one each evening for seven days about the light around them. At the end of the week, your child will discuss with you and pick one family light habit to try (open curtains in the morning, dim lights an hour before bed, phones off the dinner table, etc.). Please participate.

If anyone in your family experiences seasonal mood changes — feeling sadder, sleepier, or slower in winter — the chapter normalizes this and routes any ongoing feelings to trusted grown-ups for support. If your family uses or has used a light box with medical guidance, please share with your child that this is a real medical tool.

If at any point your child shares something concerning — about their eyes, their feelings, or anything else — please reach out. We are a team.

Thank you for being part of your child's learning.

Anticipated parent concerns and responses

• "Why doesn't the chapter teach the specific morning sunlight protocol I've heard about?" Some adult-facing wellness content prescribes specific morning light protocols (specific minutes, specific timing windows, specific lux levels). Those protocols are designed for adults and are not age-appropriate for kids age 9-10. The chapter teaches morning light as a general human practice without prescriptive numbers — what every culture has done for thousands of years. Older grade chapters will go deeper into the underlying research.
• "Why so much eye-safety content? Isn't that scary?" Solar retinopathy and laser injuries are real, preventable, and most often happen because kids did not have clear information. The American Academy of Ophthalmology and the National Eye Institute recommend age-appropriate eye-safety teaching at this grade. The chapter teaches the rules calmly, never gory, with practical guidance for what to do if something happens.
• "My child has a vision condition. Will they feel singled out?" No. The chapter explicitly includes blind kids, low-vision kids, light-sensitive kids, and migraine-prone kids matter-of-factly throughout. The body-clock teaching makes clear that vision-different kids have body clocks that work through other rhythms (meal times, schedules, sound, temperature). If you would like us to highlight or adjust anything for your child specifically, please let us know.
• "My child gets the winter blues. Should I be worried?" Mild seasonal mood changes are common and normal. The chapter teaches that ongoing or significant changes should be discussed with a trusted grown-up and, when needed, a doctor or counselor. If your child has been struggling with mood across the dark months, this chapter creates a natural opening to talk and seek support.
• "What about my child's screen time?" The chapter takes a practical approach: screens are bright tricky light that can affect the body's clock and tire eyes; trusted grown-ups set rules that fit each family. We don't prescribe specific hours or apps. Pediatric guidance (AAP) suggests screens away from bedtime at this age.

Founder review notes — safety-critical content protocol

This chapter is flagged founder_review_required: true because it covers multiple safety-critical content categories:

• Eye safety (load-bearing). The never-look-at-the-sun rule, solar retinopathy, eclipse safety, and laser safety are the chapter's load-bearing safety teachings. Citations 10, 11, 12 anchor these sections. The eclipse-safety section explicitly handles the partial-eclipse and totality cases at age-appropriate framing, with ISO 12312-2 as the only certifying standard.
• Light safety. Includes screen-time guidance, welding/bright-work light, fireworks, strong reflections, and the screens-close-to-eyes-for-hours nearsightedness content. Citation 13 anchors pediatric myopia / outdoor-time research.
• Screen time. Age-appropriate framing without specific hour prescriptions. AAP citations anchor the no-screens-before-bedtime guidance.
• Mental health vigilance / seasonal mood. Seasonal mood content is preventive and developmentally appropriate. Light-box content is framed as a real medical tool used only with a doctor's guidance. Crisis resources at age-appropriate framing.
• Vision inclusion. Blind, low-vision, migraine-prone, and light-sensitive kids explicitly included. Body-clock teaching covers vision-different pathways through other rhythms.
• Age-appropriate health messaging. No morning-sunlight protocol (no minutes, no lux measurements, no specific timing windows). No light-box prescriptions (medical-tool-with-doctor-guidance framing only). No specific screen-time hour prescriptions.
• Medical claims. All descriptive framing ("research suggests," "trusted grown-ups and doctors decide"). No prescriptive health claims.
• Crisis resources. Re-verify all phone numbers and URL currency at publication: 911 (emergencies including eye emergencies), 988 Suicide & Crisis Lifeline, Crisis Text Line (HOME to 741741), SAMHSA 1-800-662-4357, National Alliance for Eating Disorders 866-662-1235. NEDA helpline 1-800-931-2237 is non-functional as of this writing and is not cited as a referral resource.

Influence-zone discipline

K-12 influence-free zone is total exclusion — Saladino, Brecka, Hamilton, Greenfield, Huberman, Hof are absent from body content at every K-12 grade. The Light chapter is the highest-risk surface for Huberman leak because morning-sunlight is the protocol most strongly associated with his contemporary popularization. The chapter teaches morning light as a general human practice ("the morning light habit is one of the oldest human habits there is"), citing the underlying foundational research on circadian entrainment (Czeisler, Berson) without naming any contemporary popularizer. The anticipated parent / student question about "Huberman / morning sunlight protocol / lux measurements" is addressed in the Common Student Questions section with the standard response: those protocols are designed for adults, not age-appropriate prescriptions for kids age 9-10, and the chapter teaches without specific counts.

What this chapter does not teach

Specific morning-sunlight protocols (no minutes, no lux, no timing windows — Grade 8+ territory and even then descriptively, not prescriptively), the technical term ipRGC for clock cells (Grade 6+), melatonin as the named wind-down hormone (Grade 6+; framed functionally as "sleepy chemistry" or "wind-down signal" at G4), the technical term circadian rhythm (named informally as "the body's clock" or "the body's rhythm" at G4), specific blue-light wavelengths (Grade 6+; screens framed at G4 as "bright tricky light"), prescriptive screen-time hours, light-box dosing (medical-tool framing only), pandemic-era topics, or any branded protocol from any contemporary popularizer.

Lesson 1.3 special note

Lesson 1.3 carries the chapter's load-bearing safety material: solar retinopathy (which is permanent and quick), eclipse safety (with the specific ISO 12312-2 certification requirement for eclipse glasses), laser safety (cheap laser pointers can damage retinas), and seasonal mood vigilance (with trusted-adult routing and crisis-resources framing). Each section ends in clear tell a trusted grown-up directives. Crisis resources at age-appropriate "grown-ups can call these" framing follow the established pattern across the G3 cycle, G4 cycle, and the rest of the Grades 3-5 tier.

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Illustration Briefs

Lesson 1.1

• The two jobs of light in the eye. A clear, friendly cartoon-style cross-section of a child's eye with two pathways traced from the back: Path A labeled "Seeing" leading to a thought bubble with a picture of a tree, captioned "what you see"; Path B labeled "Body clock" leading to a small clock icon with sun-and-moon imagery, captioned "what time of day it is." A small friendly cluster of dot-like cells at the back of the eye is labeled "clock cells." Coach Light (the Rooster) beside the illustration, wing pointing at each pathway. Mood: clear, friendly. Include written description of the image accessible to kids with low vision.
• Day rhythm panel. A simple horizontal three-panel showing dawn (Rooster crowing as the sun rises), midday (sun high, kid playing outside), and dusk (kid winding down with a book by a lamp). Long curving arrow tying them together. Mood: peaceful, daily. Show diverse skin tones.
• Inclusion illustration. A panel showing kids with different light experiences: a kid with sunglasses, a kid with eye patches or low-vision glasses, a kid using a white cane outdoors at midday, a kid in heavy snow at midday in northern winter. The Rooster watches over all, with a small caption: "Every kid has a clock."

Lesson 1.2

• A day in light. A wide multi-panel illustration showing one kid's day: opening curtains in the morning (Rooster on the windowsill outside), walking to school in early morning sun, recess outside, family dinner with no phones at the table, evening reading in soft warm lamp light, bedtime in dark room with the Cat appearing as the Rooster hands off. Mood: peaceful, normal, doable.
• The Rooster-and-Cat partnership. A circular illustration of a 24-hour clock with the day half (top) showing the Rooster and the sun, and the night half (bottom) showing the Cat and the moon. Where they meet (sunrise and sunset) shows them touching wings/paws gently. Mood: warm, partnered, peaceful.
• Winter and summer comparison. A two-panel illustration. Left: a kid in summer waking up to bright sunlight at 6am (window full of light). Right: the same kid in winter waking up at the same 6am to a dark window with curtain partly open and a small lamp on. Mood: matter-of-fact about the difference seasons make.

Lesson 1.3

• Sun safety: never look directly. A clear, calm scene of a child outside on a sunny day, NOT looking up at the sun. Wearing a baseball cap and sunglasses, looking forward at a friend or activity. The sun is in the upper corner with a soft "do not look" symbol around it. The Rooster beside the child, also facing forward, NOT looking up. Caption near the sun: "Never look directly. Ever." Mood: calm, matter-of-fact, not frightening.
• Eclipse safety. A scene of kids watching an eclipse safely. Some kids have ISO-certified eclipse glasses on (with the certification clearly visible on the side). One kid is using a pinhole projector. A trusted grown-up nearby is helping. The Rooster sits with them, looking proud. Caption: "Only certified eclipse glasses (ISO 12312-2). Regular sunglasses are NOT safe." Mood: educational, calm, never frightening.
• Eye injury response. A calm scene of a child rubbing one eye, with a trusted grown-up immediately attentive — kneeling beside the child, ready to help, perhaps with a clean cup of water or a damp cloth. Coach Light (the Rooster) is in the background, looking attentive but not panicked. Mood: steady, prepared, "knowing what to do takes the scary out of it."
• Seasonal mood — winter. A scene of a child in winter inside near a sunny window during midday, taking a short breath in front of the bright window with a hot drink. Outside it is gray and gentle snow is falling. The Rooster is on the windowsill outside, calm. The caption: "When winter feels heavy, find the light you can." Mood: gentle, warm, hopeful, never sad-feeling.
• The Rooster's last thought. A closing illustration of the Earth from space showing the line between day and night moving across the planet, with several kids on different continents living their parallel days — one waking up, one at midday, one going to sleep — all under the same sun. The Rooster perches in the foreground. The Cat in the background. Mood: connected, peaceful, hopeful.

Aspect ratios: 16:9 for web display, 4:3 for print conversion. All illustrations show diverse skin tones, body types, hair textures, gender expressions, and abilities (including kids with mobility supports, kids using glasses, kids with low vision, kids with light-sensitivity needs). The Rooster's character design carries forward from G3 Light.

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Citations

1. Hubel DH, Wiesel TN. (1962). Receptive fields, binocular interaction and functional architecture in the cat's visual cortex. The Journal of Physiology, 160(1), 106-154. https://doi.org/10.1113/jphysiol.1962.sp006837
2. Berson DM, Dunn FA, Takao M. (2002). Phototransduction by retinal ganglion cells that set the circadian clock. Science, 295(5557), 1070-1073. https://doi.org/10.1126/science.1067262
3. Czeisler CA, Allan JS, Strogatz SH, et al. (1986). Bright light resets the human circadian pacemaker independent of the timing of the sleep-wake cycle. Science, 233(4764), 667-671. https://doi.org/10.1126/science.3726555
4. Hale L, Guan S. (2015). Screen time and sleep among school-aged children and adolescents: a systematic literature review. Sleep Medicine Reviews, 21, 50-58. https://doi.org/10.1016/j.smrv.2014.07.007
5. Lockley SW, Brainard GC, Czeisler CA. (2003). High sensitivity of the human circadian melatonin rhythm to resetting by short wavelength light. Journal of Clinical Endocrinology and Metabolism, 88(9), 4502-4505. https://doi.org/10.1210/jc.2003-030570
6. Rose KA, Morgan IG, Ip J, et al. (2008). Outdoor activity reduces the prevalence of myopia in children. Ophthalmology, 115(8), 1279-1285. https://doi.org/10.1016/j.ophtha.2007.12.019
7. American Academy of Pediatrics, Council on Communications and Media. (2016). Media and young minds. Pediatrics, 138(5), e20162591. https://doi.org/10.1542/peds.2016-2591
8. Rosenthal NE, Sack DA, Gillin JC, et al. (1984). Seasonal affective disorder: a description of the syndrome and preliminary findings with light therapy. Archives of General Psychiatry, 41(1), 72-80. https://doi.org/10.1001/archpsyc.1984.01790120076010
9. Swedo SE, Pleeter JD, Richter DM, et al. (1995). Rates of seasonal affective disorder in children and adolescents. American Journal of Psychiatry, 152(7), 1016-1019. https://doi.org/10.1176/ajp.152.7.1016
10. American Academy of Ophthalmology. (2017). Solar Retinopathy from Sun Gazing. AAO Clinical Statement. https://www.aao.org/eye-health/diseases/solar-retinopathy
11. American Astronomical Society Solar Eclipse Task Force. (2024). Eye Safety During a Total Solar Eclipse. AAS Guidelines for ISO 12312-2 certified eclipse glasses. https://eclipse.aas.org/eye-safety
12. Mainster MA, Stuck BE, Brown J Jr. (2004). Assessment of alleged retinal laser injuries. Archives of Ophthalmology, 122(8), 1210-1217. https://doi.org/10.1001/archopht.122.8.1210
13. Wu PC, Chen CT, Lin KK, et al. (2018). Myopia prevention and outdoor light intensity in a school-based cluster randomized trial. Ophthalmology, 125(8), 1239-1250. https://doi.org/10.1016/j.ophtha.2017.12.011
14. National Emergency Number Association. (2024). 9-1-1 Statistics and Public Education Materials. NENA: The 9-1-1 Association.