Moon and Tides Lab
Moon phases are one of the hardest things to teach, because students have to join two pictures in their heads: the Earth and Moon seen from far above, and the sky seen from the ground. Moon and Tides Lab shows both at the same moment, on one clock, so the join is on the screen.
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 for phases: predict what makes the Moon change shape, drag it round, test the Earth's-shadow idea, and predict again. A second period for eclipses, and a third for tides where your state teaches them.
Set up a free class Share to Google ClassroomWhat a student actually does
The screen shows the same moment twice. On the left, the Earth from far above the North Pole, lit by the Sun from one side, with a small person standing on it and the Moon going round on its path, always lit on the half that faces the Sun. On the right, what that person sees from a beach: the sky's color, the Sun if it is up, and the Moon at its real height, turned so its lit side points toward the Sun. Along the bottom, the month as a row of Moon shapes.
Before anything moves, the student picks what they think makes the Moon change shape. Then they drag the Moon a quarter of the way round, and the crescent over the beach grows into a half Moon, high in the sky at sunset. They turn on Earth's shadow and see it point straight away from the Sun, nowhere near a crescent or a half Moon, and they answer the question again. Turning the Earth shows why a half Moon is up in the afternoon and a full Moon rises as the Sun sets.
The Eclipses chapter tips the view on its edge, with heights to scale, so the Moon passes above or below Earth's shadow most months, and eclipse seasons come about twice a year. Lay the orbit flat and every full Moon is an eclipse. The Tides chapter shows the two bulges the Moon stretches in an ocean, two high tides a day, spring and neap tides, and then a real coast's tide from NOAA's measured numbers, from Boston's two equal tides to Pensacola's one a day. Real dates puts the real Sun and Moon over any of 17 places, and Tonight's Moon asks the student to predict tonight's Moon, then go out and look.
A total eclipse of the Moon. The side view keeps heights to scale, so it shows why most full Moons miss Earth's shadow: the Moon's path is tipped about 5 degrees, and only when a full Moon comes while the Sun is lined up with the crossing points does the Moon go in.
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 |
|---|---|
| Drags the Moon round and watches its shape change over the beach | Phases come from how much of the lit half we see. The Sun always lights half of the Moon. As the Moon goes round the Earth, we see different amounts of that lit half: none at new Moon, half of it at the quarters, all of it at full Moon. |
| Turns on Earth's shadow at a crescent | The shadow is not the cause. Earth's shadow points straight away from the Sun. At a crescent or a half Moon the Moon is nowhere near it, and it still has a shape. The shadow only touches the Moon during an eclipse. |
| Turns the Earth with the person standing on it | Where the Moon is in the sky. The phase stays the same all night; what changes is where it is. A half Moon is up from about noon to midnight, a full Moon from sunset to sunrise, and the Moon comes up about 50 minutes later each day. |
| Tips the view on its edge and lays the orbit flat | Why eclipses do not happen every month. The Moon's path is tipped about 5 degrees. Most new and full Moons pass above or below the shadows. Eclipses come only when a new or full Moon happens while the Sun is lined up with the crossing points, about twice a year. |
| Finds a lunar eclipse and a solar eclipse seen from home | Who sees an eclipse. In a lunar eclipse the Moon itself is in Earth's shadow, so anyone with the Moon up sees it. In a solar eclipse the Moon's shadow touches only a narrow path of the Earth. |
| Watches the arrows round the Earth and turns a beach through a day | Two bulges, two high tides. The Moon pulls the near side of the Earth more and the far side less than the middle. What is left stretches the ocean both ways, and a turning beach passes through both bulges. |
| Adds the Sun and looks at a month of tides | Spring and neap tides. Lined up with the Moon at new and full Moon, the Sun's smaller stretch adds to the Moon's: spring tides. At the half Moons it works across it: neap tides. |
| Picks Pensacola after Boston | A real coast is not an ocean planet. The shape of the ocean and the coast decides the timing and the size of the tide. Some coasts get one high tide a day, and some get six meters. |
How to tell whether it landed
Ask, and let them show you. A student who has understood it can answer these without help.
- Why is it not Earth's shadow that makes the Moon change shape?
- Where is a half Moon in the sky at sunset? Why can you also see it in the afternoon?
- There is a full Moon every month. Why is there not an eclipse of the Moon every month?
- Why can everyone on the night side see an eclipse of the Moon, but only a narrow path sees a total eclipse of the Sun?
- Why are there two high tides a day, and not one?
- Why are the tides bigger at new and full Moon than at a half Moon?
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 directly: a model of the Earth, Sun and Moon to describe the cycles of phases and eclipses, with the predictions its evidence statement asks for (the phase from the positions, the positions from the phase, whether an eclipse is seen from a place), and the scale limits named on screen.
State standards with tides
Texas TEKS 6.9(B) (daily, spring and neap tides), Virginia SOL 6.3, Florida SC.8.E.5.9 and New York HS-ESS1-7 teach tides with the Moon. The Tides chapter is for those classes; a teacher in an NGSS state can turn it off in Setup.
High school Earth science and physics
The same views with the angles, the lit-fraction formula, the eclipse geometry, the tide's one-over-distance-cubed and a station's tide constituents. HS-ESS1-4 for the orbit and the ratios.
Homeschool and co-ops
Tonight's Moon turns the app into a week of real observing: predict from the model, go out at 9 pm, log what you saw, cloudy nights included.
Practical notes
- AgesGrades 6 to 8 are the home ground: the screen speaks in phases, compass directions, clock times, low and high in the sky, and meters of tide. The high school level adds the angles and the formulas for grades 9 and 10.
- TimeOne period for phases. One for eclipses. One for tides, where your state teaches them.
- EquipmentA computer or Chromebook with a modern browser. Nothing to install. A projector for Big screen. A lamp and a foam ball if you also do the classic phases lab: the app is the view from above that the lamp lab cannot give.
- CostFree. The app has no paid tier.
- PrepRun the Phases guide once 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 place for the class, whether real dates are allowed, 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 and hand the project out as the starter; the chapters, the place and the questions travel with it. With a free account the students' sheets come back to you as saved projects, with their predictions before and after, the puzzles they solved and their Moon log.
Common questions
Is it free?
Yes. Moon and Tides Lab has no paid tier, and it can be tried right on this page without an account.
Does it replace the lamp and foam ball lab?
No, it finishes it. The lamp lab gives the view from the ground; the app adds the view from above at the same moment, and the 5 degree tilt that the lamp lab hides when students hold the ball up to keep it out of their head's shadow.
Is it to scale?
No drawing of the Earth and Moon can be, and every view says so. The Moon is drawn closer and bigger so it can be seen (a switch puts it at its real distance, 30 Earth-widths away). The side view keeps heights to scale and squeezes distances. The tide bulges are drawn about 4 million times too big.
Are the real dates and eclipses accurate?
Real dates uses Astronomy Engine. Every 2026 new and full Moon in it falls within 2 minutes of the US Naval Observatory's times, and the 2024 eclipse's totality over Dallas starts and ends within seconds of theirs. The eclipse paths across the Earth are worked out simply: good for learning, not for planning a trip.
Are the tides accurate?
Real coast uses NOAA's measured tide constants for twelve US stations. At eleven of them the app is within a few centimeters of NOAA's own tide tables. At Anchorage, where the tide is huge and the water shallow, it is good to about a quarter of a meter. It is for learning, not for boating.
Tides are not in MS-ESS1-1. Why are they here?
The framework behind NGSS names tides in the same sentence as eclipses, and Texas, Virginia, Florida and New York teach them with the Moon. Teachers who do not need them can turn the Tides chapter off in Setup.
What does it simplify?
In Model mode the Earth's own tilt and the seasons are left out and the clock is sun time; the Moon's path is a circle whose distance changes a little. The tide bulges are the tide on a planet covered in ocean; real tides are shaped by the oceans, which is why Real coast uses measured numbers. Each simplification is named in How it works.
Is the eclipse safety right?
Every solar eclipse card carries it: eclipse glasses made to the ISO 12312-2 standard, never sunglasses, a pinhole viewer with your back to the Sun, bare eyes only during totality, and never a camera, binoculars or a telescope without its own solar filter.
Does it run on Chromebooks?
Yes. It draws in 2D in the browser with nothing to install, and it has a Big screen mode for a projector.
Still have a question? Ask us, and a person will write back.
Where to go next
Badge kits and learning kits
Step-by-step projects in Moon and Tides Lab that end with a certificate: for a scout badge, or for homeschool families and classes.
- Catch the Moon: Learning kit badge, or the learning kit for grades 6-8
Lesson plans
4 ready-to-teach class periods with a teacher plan, a student worksheet, an exit ticket with answers, and the standards it meets.
Start with Moon and Tides Lab
Trying it costs nothing and takes about five minutes. An account is what makes the work last.
Moon and Tides Lab is one of the making apps on the platform. Tide constants are from NOAA's Center for Operational Oceanographic Products and Services; the real Sun and Moon are from Astronomy Engine by Don Cross.
Page last reviewed November 2026.
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