Seed Lab
Ask a class where a plant's mass comes from and most will say the soil. College students say it too. The real answer, the air, is hard to see in a cup on a windowsill: the gain is too small to weigh, the dry mass needs an oven, and the air is invisible. Seed Lab grows one plant in a pot with a glass front, hour by hour, and keeps the books on every gram of it.
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: guess where the plant's weight will come from, plant a bean and watch the root come first, open the ledger once it is up, then run it outdoors to ripe seeds and compare the jars with the guess. Weigh the soil before and after.
Set up a free class Share to Google ClassroomWhat a student actually does
A clay pot with a glass front sits on a windowsill, so the soil is a cutaway with a ruler on the glass. The student picks a seed (bush bean, pea, sunflower or radish), a pot size and a soil, drags the seed into the soil to the depth they choose, and taps where they think the plant's weight will come from: soil, water, air, sunlight. Then the days run, with the sun crossing the window and night falling.
The seed swells, the first root comes out and turns down whatever way the seed was lying, and a pale hook pushes up through the soil. A bean lifts its seed halves out of the ground; a pea leaves its seed below. Once it is up, the ledger opens: four jars that keep the books on the plant's dry mass. The seed jar goes down first, because the seedling is burning the food packed in the seed. Then the air jar climbs.
Students change one thing at a time: the window or the closet, a grow light or outdoors, the water, the warmth and a heat mat, the pot and the soil, fertilizer. They turn the pot and lay it on its side to watch new growth bend toward the light and away from gravity. They run it to flowers and ripe seeds, count the seeds and plant one as the next generation. A slider goes back to any earlier day to try a different choice from there.
A bush bean grown outdoors in a 1.5 liter pot: 14.5 g of dry plant, and only 0.71 g of it came from the soil. Almost all of it was carbon dioxide from the air. About 8.8 liters of water went in at the roots and out at the leaves on the way.
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 air jar fill while the soil jar barely moves | Where a plant's mass comes from. Most of a plant's dry mass is carbon and oxygen from carbon dioxide in the air. Water gives the hydrogen. Only about 4 grams in every 100 come from the soil. |
| Sees the dry mass fall after planting, then climb once the leaves open | Food stored in a seed. A seedling lives on the food packed in its seed until its leaves can make sugar from light. |
| Puts a bean in the closet and watches it sprout anyway | What a seed needs to sprout. A seed needs water, warmth and air to sprout. Light matters only once it has leaves. |
| Lays the pot on its side and turns it | Gravitropism and phototropism. Roots grow toward gravity and shoots away from it; shoots also bend toward the brighter side. |
| Reads the water that passed through the plant | Transpiration. Hundreds of grams of water go in at the roots and out at the leaves for every gram the plant keeps. |
| Brushes a sunflower indoors, and finds a lone radish sets almost no seed | Pollination. Beans and peas pollinate themselves; a sunflower needs bees or a brush; a radish needs pollen from another radish. |
| Changes one thing and compares the jars | Fair tests. Light, water, warmth and the pot each change how big the plant gets; only one can change at a time if you want to know which did it. |
How to tell whether it landed
Ask, and let them show you. A student who has understood it can answer these without help.
- Where did most of your plant's dry mass come from? How do you know?
- Why did the dry mass go down before it went up?
- The bean in the closet sprouted. So does a seed need light?
- Your plant took in liters of water but kept only a few grams of it. Where did the rest go?
- Your soil lost less than a gram. Your plant gained grams. Where did the difference come from?
- Why did the radish set almost no seed on its own?
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.
Grades 3 to 5 life science
3-LS1-1 life cycles of flowering plants, seed to seed; 4-LS1-1 roots, stems, leaves and flowers; 5-LS1-1 most of all: plant matter comes mostly from air and water, not from the soil. A grades 3 to 5 level shows the jars with no numbers.
Middle school life science
MS-LS1-6 photosynthesis as matter moving into the plant, with inputs and outputs only; MS-LS1-5 light, water, warmth and pot size changing growth; MS-LS1-4 flowers, pollination and seeds.
High school biology
HS-LS1-5 and HS-LS2-5: the ledger in grams with the sugar equation, respiration day and night, and a second honest way to count the books, by what goes in and out.
State standards that name it
Texas 3.13 B (radishes and lima beans), 8.6 E (conservation of mass including photosynthesis); Virginia 4.2 (carbon dioxide, water and sunlight make sugar); Florida SC.3.L.14.2 (stems toward light, roots down with gravity).
Practical notes
- AgesGrades 5 to 8 are the home ground. A grades 3 to 5 level shows the jars without numbers. A high school level adds degree days, light in mol, and the books counted a second way.
- TimeOne period to guess, plant, watch it come up and open the ledger, then run a plant outdoors to ripe seeds. A second for one change at a time, the closet and the pot on its side, the puzzles and the sheet.
- EquipmentA computer or Chromebook with a modern browser. Nothing to install. For the real thing: a dry bean from the grocery store, a paper towel and a zip bag; the app prints a bean in a bag sheet and takes your real counts beside its own.
- CostFree. The app has no paid tier.
- PrepAbout ten minutes: plant a bean on the south window, open the ledger once it is up, then plant one outdoors at a day a second and run it to ripe seeds, so you know what students will see.
- In a groupOpen the Sheet, then Setup: which seeds and lights students can choose, whether the fastest speed is allowed, a guess before Start, weekend cooling, the puzzles, and an answer key worked out from the model.
For co-ops, microschools, and classrooms
Every run is the same: the same seed in the same pot and room comes up on the same day and makes the same seeds, so a class can compare plants fairly and put its numbers on one table. Real beans vary; pair the app with a bean in a bag and put the real counts in the journal beside the app's.
Common questions
Is it free?
Yes. Seed Lab has no paid tier, and it can be tried right on this page without an account.
Does it replace growing a real plant?
No. Grow one too. The app shows what a cup on a windowsill cannot: the roots, the hours at night, the dry mass and where it came from, and weeks that would run past a school break. It prints a bean in a bag sheet, and the journal takes your real plant's height beside the model's.
Where do the numbers come from?
How fast seeds come up at each soil temperature comes from published germination tables. Growth runs on degree days, light caught by the leaves, and respiration day and night, with water use from the standard crop tables. Some values are our own estimates, and the teaching notes say which.
Why does a plant on a sunny windowsill stay so small?
Because a windowsill is dim. A bright south window gives a plant about a fifth of the light it would get outdoors in summer. Move the pot outdoors or under a grow light and the same seed grows several times bigger.
Is the plant the same every time?
Yes. That makes fair comparisons possible, but real plants vary: some seeds come up early, some late, some not at all. Seeds from one plant differ a little in size, and that carries into the next generation.
Why is it only 4 grams in every 100 from the soil?
Dried plant matter is about 45 parts carbon, 45 oxygen and 6 hydrogen, which come from carbon dioxide and water. The rest is nitrogen and minerals from the soil. A young, fast-growing plant can have up to about 8 in every 100.
What does it leave out?
Pests, mold, wind and how humid the room is. Flowers that bees visit outdoors are pollinated in the model without the bees drawn. A radish is self-incompatible, so one radish alone sets almost no seed; the app does not yet grow two side by side.
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 Seed Lab that end with a certificate: for a scout badge, or for homeschool families and classes.
- Bean in a bag: Learning kit badge, or the learning kit for grades 3-8
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 Seed Lab
Trying it costs nothing and takes about five minutes. An account is what makes the work last.
Seed Lab is one of the science labs on the platform. It steps one plant an hour at a time, replays the plant from what the student did, and its test suite checks it against published germination tables and keeps the ledger's books balanced to the microgram every hour of every run.
Page last reviewed November 2026.
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