Teaching with Watershed Lab
For earth science and environmental science teachers, elementary teachers, co-op leaders and parents. One period on rain, land and runoff, one on finding a polluter by sampling the creek, what students get wrong and where the app answers it, and the sheet and the setup.
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 Classroom- About these notes
- Period one: rain, land and runoff
- Period two: find the source
- What students get wrong, and where the app answers it
- What the app simplifies, on purpose
- Grades 2 to 5, middle school and high school
- The sheet and the setup
- Standards
About these notes
Watershed Lab is a valley on a tabletop, about four kilometers across, with its hills drawn five times taller than real. Students shape the land, cover it with forest, farms, a town or pavement, and rain a real storm on it. The water runs down every slope into the creeks, a gauge draws the rain and the creek's rise, and the yellow divide shows the edge of the watershed. In Find the source they test creek water in up to eight vials to find which place upstream is fouling the beach.
The runoff is worked out the way engineers do it, with curve numbers for each land cover and soil (NRCS TR-55), and the three storms are central Iowa's: the biggest rain of a usual year, a storm that comes about every other year, and the once in a hundred years. Every reading has its unit and the line where it becomes a problem.
Period one: rain, land and runoff
- The first storm (10 minutes) Everyone opens Millbrook Valley, picks Big storm and presses Rain. Water runs down the slopes and the creeks swell. When it ends the yellow divide appears. Ask: rain that fell a step outside the yellow line, where did it go?
- Pave it (10 minutes) Pick Cover the land, paint a town and a parking lot across the valley above the creek, and rain the same storm again. Compare the two curves on the gauge: the paved valley's creek rises higher and sooner. On loam in the Big storm, about 92 of every 100 drops run off a parking lot and about 7 off a forest.
- The soil and the dye (10 minutes) Change the soil from sandy to clay and rain again. Then turn on Dye: green is fertilizer, brown manure, black and gray oil off pavement, tan soil. Ask where the brown in the creek starts.
- Shape it (10 minutes) In Shape the land, raise a ridge across the valley. A pond fills behind it. Ask why the water stopped there, and where it goes when the pond is full.
- Wrap up (5 minutes) Pick Follow a drop and click the land high up the valley: the drop's path is drawn down to the creek, and the card says where it leaves the table and about how long it takes. Click just outside the yellow line and compare. Then the first questions on the sheet.
Period two: find the source
Pick Find the source. Each mystery is a new valley with six to eight places on its creeks, one of them leaking: germs at the beach, algae in the pond, an oily sheen, or a creek that runs brown on a dry day. The story names what to test for. Students fill vials by clicking the creek and read each one on its 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.
The rule they discover: water below a leak tests high and water above it tests clean. Testing just above where two creeks join rules out one branch with one vial. A hint shows the spot that rules out about half of the places still possible, but costs a vial. Par is shown before the first vial, so students can compare.
For the whole class, set Setup to shared mysteries so every student gets the same valleys, then compare vial counts and the order they tested in. The fewest vials comes from halving the possibilities each time, the same idea as a binary search.
What students get wrong, and where the app answers it
| What students say | Where the app answers it |
|---|---|
| Storm drains go to the treatment plant | In town the grate, the pipe under the street and the pipe end on the creek bank are drawn, and the dye goes straight through. In surveys of adults, a quarter thought so and a third did not know |
| Groundwater is an underground river or lake | The creek keeps running for days after the rain stops; the help says that water seeps out of soil and rock, not out of a hidden river |
| Only the land right next to the creek matters | Rain anywhere inside the yellow divide ends up in this creek; paint a town far up the valley and the creek still rises |
| Pollution comes out of pipes | Fertilizer, manure and oil wash off whole fields and streets with the rain, shown by the dye; the leaking places in the mysteries are only one kind |
| Forest stops all runoff | On clay, or in the hundred year storm, a third of the rain runs off even a forest |
| Clear water is clean water | A clear creek can carry E. coli or nitrate; the mysteries test for what you cannot see |
What the app simplifies, on purpose
- E. coli is an indicator: most E. coli are harmless, and other germs that come with sewage or manure cause most illness.
- The E. coli dish is a 1 mL sample, so one spot is 100 per 100 mL and the 235 line is two or three spots. Beach labs test 100 mL.
- An oil sheen shows oil is there, not how much. A natural sheen from iron bacteria breaks into flat pieces when poked; oil swirls back together.
- Low places fill as ponds as soon as water reaches them. Real ponds take many storms to fill, and some never do, because water soaks in or dries up.
- Algae in a real pond often depends more on phosphorus than on nitrate. The app tests only nitrate.
- In tile-drained farmland much of the nitrate reaches the creek underground, between storms. The app sends it both ways, with the storm and with the groundwater.
- Runoff starts once the ground has held 0.2 of its capacity, TR-55's standard. Newer NRCS work suggests less, about 0.05.
Grades 2 to 5, middle school and high school
| Grades 2 to 5 | Middle school | High school | |
|---|---|---|---|
| Readings | In words and pictures: a lot, some, very little | In their units: per 100 mL, mg/L, NTU | In their units |
| Flow | In bathtubs a second | In bathtubs a second, with the gauge | The same, with curve numbers on the cards |
| Sheet questions | Six, in simpler words | Eleven | Twelve, with the curve number question |
The sheet and the setup
The Sheet in the app's header is the student's write-up: a picture of their valley with its divide, the storms they ran with how much ran off, the sources they found, and the questions. They hand it in and it saves with the project, or print it.
Setup sets the level, whether each student gets their own mysteries or the class shares the same ones, which questions are on the sheet, up to ten of your own, and prints an answer key. Set it on a starter project and hand that out: the setup travels with it.
Standards
No NGSS performance expectation uses the words watershed or runoff. These are the ones the app's work fits.
- MS-ESS3-3: design a method for monitoring and minimizing a human impact on the environment (Find the source is the monitoring; repainting the land and raining again tests ways to minimize it).
- 5-ESS2-1: the geosphere and hydrosphere interacting (rain running over shaped land).
- 4-ESS2-2: patterns in maps, topographic maps named (the Map view with contour lines every 10 meters).
- 2-ESS2-2: model the shapes and kinds of land and water in an area (Shape the land).
- HS-ESS3-4: evaluate a solution that reduces human impact, using data (the same storm on different land, and the readings).
- Virginia science 4.8 and 6.8, and Maryland's environmental literacy requirement, name watersheds directly.
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Page last reviewed November 2026.
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