Watershed Lab
A watershed model on a table is something most classes see once a year, as a demo. Watershed Lab puts one in front of every student: shape the land, rain a real storm on it, pave part of it and rain again, then find which place upstream is fouling the beach.
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: rain the Big storm on the forest valley, pave a town across the creek and rain it again, and compare the two curves on the gauge. A second period: Find the source, with the vials, the test kits and the sheet.
Set up a free class Share to Google ClassroomWhat a student actually does
A valley sits on a wooden tabletop, about four kilometers across, with its hills drawn five times taller than real so the shape reads at a glance. The student presses Rain and picks a storm: the biggest rain of a usual year, a storm that comes about every other year, or the once in a hundred years. Rain falls, water runs down every slope, and the creeks swell and turn brown with mud. A gauge beside the table draws the rain as bars and the water at the creek mouth as a curve, and the yellow line around the edge shows the watershed's divide.
In Shape the land the student raises ridges, digs valleys and builds a dam, and a pond fills behind it. In Cover the land they paint forest, meadow, pasture, a cornfield, houses and lawns, a town, a parking lot or a construction site, pick the soil under it all, and rain the same storm again. Dye shows where each kind of water comes from: green for fertilizer, brown for manure, black and gray for oil off pavement, tan for soil. Follow a drop shows the way one raindrop takes to the creek, and storm drains in town are grates, a pipe under the street and a pipe end on the bank.
Find the source is a mystery: the beach has germs, algae, an oily sheen, or mud on a dry day, and one place on the creeks is to blame. The student fills up to eight vials of creek water and reads each one on a real-looking test: purple spots on an E. coli dish, a nitrate strip against its chart, a turbidity tube read in centimeters, a tray for an oil sheen. Water below the leak tests high and water above it tests clean, so testing just above where two creeks join rules out half the places at once. A hint shows that spot but costs a vial. When they name the right place, the app shows the leak's path to the beach and how many vials it took.
An E. coli mystery solved with hints. Each pin is a vial of creek water with its reading: clean water above the leak, high below it. The check marks the cabin whose septic tank is cracked.
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 rain on one side of the yellow line run to a different creek | A watershed and its divide. All the land that drains to one place is its watershed. The ridge line around it is the divide: rain a step outside it ends up somewhere else. |
| Paves a town over forest and rains the same storm again | Runoff and land cover. Roofs and pavement let almost no water in, so more of the rain runs off, faster, and the creek rises higher and sooner. Forest soaks most of an ordinary storm in. |
| Rains the same storm on sand and then on clay | Infiltration. Sand takes water in quickly. Clay's tiny spaces let it in slowly, so more of the rain runs off the top. |
| Sees the creek still running days after the rain | Groundwater and baseflow. Rain that soaked in moves slowly through the ground and seeps out into the creek between storms. It is water in soil and rock, not an underground river. |
| Follows the dye from a farm field and a parking lot | Nonpoint source pollution. Fertilizer, manure and oil wash off a wide area with the rain. No single pipe to point at makes it the hardest kind to clean up. |
| Tests just above where two creeks join | Monitoring by sampling. Water below a leak carries it and water above does not, so each well-placed vial rules out a branch. Water quality staff find sources the same way. |
| Reads a turbidity tube and counts spots on a dish | Water quality measures. Each test measures one thing in its own unit: E. coli per 100 mL, nitrate in mg/L, mud in NTU, oil in mg/L, each with the line where it becomes a problem. |
How to tell whether it landed
Ask, and let them show you. A student who has understood it can answer these without help.
- Rain fell just outside the yellow line. Why did it not end up in this creek?
- The town and the forest got the same rain. Why did the creek below the town rise faster and higher?
- Where does the water that goes down a storm drain in town end up? Is it cleaned on the way?
- The rain stopped days ago, but the creek is still running. Where is that water coming from?
- Why is it smart to test just above where two creeks join, instead of anywhere?
- Name two changes upstream that would keep the beach cleaner, and say how each one works.
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 science
MS-ESS3-3 most directly: Find the source is a method for monitoring a human impact on water, and repainting the land and raining again tests ways to reduce it. The clarification names land usage, urban development and agriculture, and water pollution, all on the table. No NGSS performance expectation uses the word watershed; this is where the idea lives.
Elementary science
5-ESS2-1, the land and the water interacting as rain runs over shaped ground; 4-ESS2-2, the Map view's contour lines; 2-ESS2-2, modeling the shapes of land and water in Shape the land. At the grades 2 to 5 level readings are in words and pictures.
High school environmental science
HS-ESS3-4: compare land uses with the same storm, using the runoff numbers and the pollutant readings as data. The high school level adds the curve numbers engineers use and the harder questions.
State watershed standards
Virginia science 4.8 and 6.8 and Maryland's environmental literacy requirement name watersheds directly. The app's storms are real ones for central Iowa, and the readings use EPA and state lines.
Practical notes
- AgesGrades 6 to 8 are the home ground. Setup has a grades 2 to 5 level, with readings in words and pictures and simpler questions, and a high school level with curve numbers and the harder questions.
- TimeOne period to rain, shape, pave and compare. A second for Find the source and the sheet. A mystery takes most students ten to fifteen minutes.
- EquipmentA computer or Chromebook with a modern browser. Nothing to install. A projector works well for the first storm with the whole class; on a phone or a narrow window the table and the bench stack and the page scrolls.
- CostFree. The app has no paid tier.
- PrepAbout ten minutes: rain the Big storm on Millbrook Valley, paint a town across the creek and rain it again, then solve one mystery with Hint. That is the whole arc of a period.
- In a groupOpen Setup in the app's header: the level, whether every student gets their own mysteries or the class shares the same ones, which questions are on the sheet, your own questions, 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 setup travels with it. With shared mysteries the whole class works on the same valleys, so students can compare how many vials they needed. With a free account the students' sheets come back to you as saved projects.
Common questions
Is it free?
Yes. Watershed Lab has no paid tier, and it can be tried right on this page without an account.
Does it replace a real watershed model or stream table?
No. Pouring water on a real model, or spraying a crumpled paper watershed, is worth doing. The app adds what a table cannot: land a student can reshape, the same storm twice for a fair comparison, and pollution to measure and trace.
How real are the numbers?
The runoff uses the curve numbers engineers use (NRCS TR-55) for each land cover and soil, and the storms are central Iowa's rainfall for a usual year, about every other year, and once in a hundred years. Pollution readings are in the range measured in real runoff, and the problem lines are EPA's and the states': 235 E. coli per 100 mL for a swimming advisory, 10 mg/L nitrate for drinking water.
What does it simplify?
E. coli is a sign of sewage or manure; other germs that come with it cause most illness. The E. coli dish is a 1 mL sample, where beach labs test 100 mL. An oil sheen shows oil is there, not how much. Low places fill as ponds at once, where real ones take many storms, and some never fill. Algae in a real pond often depends more on phosphorus than on the nitrate the app tests.
Why does a storm drain matter so much?
In most towns the storm drain pipe is separate from the sewer, so whatever washes into a grate goes to the creek untreated. Surveys find many adults think otherwise. In the app the grate, the pipe under the street and the pipe end on the creek bank are drawn, and the dye goes straight through.
Does it run on Chromebooks?
Yes. It runs in the browser with nothing to install. In a narrow window the table and the tools stack and the page scrolls.
Is there a grade level setting?
Yes, in Setup: grades 2 to 5, middle school, and high school. Each changes how readings are shown and which questions are on the sheet.
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 Watershed Lab that end with a certificate: for a scout badge, or for homeschool families and classes.
- Follow the rain: Learning kit badge, or the learning kit for grades 4-8
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 Watershed Lab
Trying it costs nothing and takes about five minutes. An account is what makes the work last.
Watershed Lab is one of the making apps on the platform. Each cell of the land is 30 meters across, the hills are drawn five times taller than real, and the Map view draws a contour line every 10 meters.
Page last reviewed November 2026.
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