Sun and Seasons Lab
Ask a room why it is warmer in summer and most of it will say Earth is closer to the Sun. Even students who say "tilt" often mean the half that leans toward the Sun is closer. Sun and Seasons Lab lets them test that idea with numbers from their own town, and find that Earth is closest to the Sun in January.
Using this with a class? Make a free class and add your students yourself: each gets a username and password, with no email or Google account needed. Or give them one join code. Using Google Classroom? Post the link there; with a free class, the link also puts each student in your class, so you see their work. mytekDev is also available from the Google Workspace Marketplace, so your school's Google admin can install it for everyone.A first lesson: One period: predict why summer is warmer, watch a stick's shadow at noon in June and December in your town, find the day Earth is closest to the Sun, compare with Sydney, and predict again. A second period for the Sunlight chapter and a real shadow outside.
Set up a free class Share to Google ClassroomWhat a student actually does
The screen shows one moment three ways. On the left, a schoolyard in the student's town, with a stick standing on a blacktop pad marked in meters, the Sun's path across today's sky, and the stick's shadow pointing away from the Sun. On the right, Earth going round the Sun, its axis tilted and pointing toward the North Star all year. Along the bottom, the town's daylight and the noon Sun's height for every day of the year.
Before anything moves, the student picks why they think summer is warmer: Earth is closer to the Sun, our half leans closer, the Sun is higher and up longer, or the axis flips toward the Sun. Then they press Play and watch the shadow shrink to its shortest at sun noon, which in Denver in June is 1:02 on the clock, not 12:00. They move to December and the Sun stays low, the day lasts 9 hours 21 minutes, and the noon shadow is twice as long as the stick. Then they drag Earth round its orbit and find the day it is closest to the Sun: early January, in the northern winter. Sydney, on the same day at the same distance, has summer. They answer the question again.
The Sunlight chapter shows a beam of sunlight a meter wide spreading over more ground as the Sun gets lower, and a size test: in Denver a summer day gets about 3 times as much sunlight as a winter day, while Earth's changing distance changes sunlight by only about 7 percent. Find my town searches 34,000 towns (or a tap on a map), and Measure a real shadow checks a stick outside against the app.
January 3: Earth is as close to the Sun as it gets all year, and Denver's noon Sun is low and its shadows are long. The north end of the axis leans away from the Sun. Distance changes sunlight by only about 7 percent; the angle and the length of the day change it about 3 times.
What they are learning while they work
Nothing here is presented as a lesson. This is what the activity is made of.
| What the student does | What it is |
|---|---|
| Watches the stick's shadow through a June day and a December day | The Sun's height changes with the seasons. In summer the noon Sun is high and shadows are short; in winter it is low and shadows are long. In Denver a 1 meter stick's noon shadow is about 0.3 m in June and 2 m in December. |
| Reads the daylight band on the year graph | Day length changes with the seasons. Denver gets about 15 hours of daylight on the June solstice and about 9 hours 21 minutes on the December one. Near the equator the day stays close to 12 hours all year. |
| Watches a beam of sunlight land on the ground | Low sunlight is spread out. A beam from a low Sun covers more ground, so each square meter gets less. That, with the shorter day, is what makes winter colder. |
| Drags Earth to the day it is closest to the Sun | Distance is not the cause. Earth is closest to the Sun in early January, during the northern winter. Its distance changes by about 3 percent, which changes sunlight by about 7 percent, far less than the angle and day length do. |
| Switches to Sydney on the same day | The two halves of Earth have opposite seasons. One Earth, one distance, two opposite seasons. In December the south end of the axis leans toward the Sun. |
| Turns on the wrong axis, and moves the tilt slider to 0 | The axis keeps its direction, and the tilt makes the seasons. An axis that turned to face the Sun would give the north summer all year. With no tilt at all, almost every place would get about 12 hours of daylight all year and there would be no real seasons. |
| Measures a real stick's shadow and checks it | The model matches the real sky. The Sun's height from a shadow is atan(stick / shadow). The app counts a reading within 2 degrees of its own as a match, about as close as a stick and a ruler can get. |
How to tell whether it landed
Ask, and let them show you. A student who has understood it can answer these without help.
- Earth is closest to the Sun in early January. Why is that not summer in the United States?
- Why is a stick's noon shadow longer in winter than in summer?
- Why does Sydney, Australia, have summer in December?
- Some people say the half of Earth that leans toward the Sun is closer, so it is warmer. Why does that not work?
- What would the seasons be like if Earth's axis were not tilted?
- The longest day is in June, but the hottest days come in July. Why?
Use it in your subject
Not a technology class? Then the app is how students show what they learned in your unit. More projects for every subject.
Middle school Earth and space science
MS-ESS1-1, the seasons part: a model of the tilted Earth, its orbit and the Sun, with the two predictions its evidence statement asks for (the season from the positions and a place, the positions from a season and a place), and the scale limits said on screen. Texas TEKS 6.9(A): model and illustrate how the tilted Earth revolves around the Sun, causing changes in seasons.
Grade 5
5-ESS1-2: daily changes in the length and direction of shadows, and day and night. Setup can turn off the Tilt and Orbit and Sunlight chapters, since grade 5 leaves the cause of seasons out.
High school Earth science
The same views with the angles and the formulas: the noon Sun's height, day length, the equation of time, sunlight in watts per square meter, latitude from a shadow, and the tilt's slow 41,000 year swing.
Homeschool and co-ops
A stick in the yard and Measure a real shadow turn the app into a real observation: predict the noon shadow, measure it, check it, and do it again a few weeks later.
Practical notes
- AgesGrades 6 to 8 are the home ground: the screen speaks in hours of daylight, the Sun low, halfway up or high, meters of shadow, and "times as much" sunlight. The high school level adds the angles and the formulas. Grade 5 can use the shadow chapter alone.
- TimeOne period for the first five minutes and the distance test. A second for Sunlight, the puzzles and a real shadow outside.
- EquipmentA computer or Chromebook with a modern browser. Nothing to install. A projector for Big screen. A straight stick and a tape measure for the real shadow, on a sunny day.
- CostFree. The app has no paid tier.
- PrepPick your own town once with Find my town and run the guide yourself, about five minutes. That is the whole demo.
- In a groupOpen Setup in the app's header: the level, which chapters students can open, whether the guide is on, one fixed town for the class, whether the tilt slider is on, the sheet's questions and up to ten of your own, and a printed answer key.
For co-ops, microschools, and classrooms
Set it up once in Setup with your town fixed, and hand the project out as the starter; the town, the chapters and the questions travel with it. With a free account the students' sheets come back to you as saved projects, with the first idea each student picked, their predictions before and after, the puzzles they did and their real shadow readings.
Common questions
Is it free?
Yes. Sun and Seasons Lab has no paid tier, and it can be tried right on this page without an account.
Does it know where my students are?
No. The app never reads a device's location. A student types a town's name (from a list of places with 15,000 people or more) or taps a world map; a spot tapped on the map is kept only to the nearest whole degree, with no name.
Are the numbers right?
Sunrise, sunset and sun noon come from NOAA's solar calculator equations, checked against the US Naval Observatory for six towns from Quito to Tromso on three days of 2026: every time matched to the minute. The solstices, equinoxes and Earth's closest and farthest days come from Astronomy Engine. Real sunrise can differ by a minute or so with the air and your horizon.
Does it replace the lamp and globe lab?
It helps it. With a lamp a few feet away, the half of the globe nearer the lamp really is closer, which teaches the wrong idea, and students tend to turn the axis to face the lamp. The app keeps the axis pointing one way and puts the distance in real numbers.
Is it to scale?
No drawing of Earth and the Sun can be, and the picture says so: Earth is drawn thousands of times too big. The orbit is seen at a slant, so it looks oval; Orbit from above shows that it is almost a perfect circle.
What does it simplify?
The sunlight numbers are for the top of the air, before clouds and the air soak up any, so they show only what the angle, the day's length and the distance do. Temperature is left out, apart from a card on why the hottest days come weeks after the longest one. Sunrise is for flat ground with no hills or buildings.
Is it safe to do the real shadow outside?
Yes, if no one looks at the Sun. Students look at the shadow and measure it, never the Sun. The app says so in the real shadow box.
Still have a question? Ask us, and a person will write back.
Where to go next
Start with Sun and Seasons Lab
Trying it costs nothing and takes about five minutes. An account is what makes the work last.
Sun and Seasons Lab is one of the making apps on the platform. The Sun's position comes from NOAA's solar calculator equations; the solstices and Earth's closest and farthest days from Astronomy Engine by Don Cross; town names from GeoNames (CC BY 4.0).
Page last reviewed November 2026.
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