Classroom activity Grade 3 Engineering & Design
Sedge Creek Farm Irrigation Channel Design Challenge
A grade 3 engineering activity where teams build and fair-test a tray channel that carries water from a well to three crop rows with the least spill.
Objectives
- Students will build a channel that carries water from a well to three crop rows.
- Students will run a fair test that changes only the channel shape.
- Students will compare two channel designs and choose the one with the least spill.
Vocabulary
Key words: channel, irrigation, fair test, spill
Teacher overview
This is a hands-on building challenge for teams of three to four students. Sedge Creek Farm has a well on one side of the field and three rows of crops on the other, and the farmer needs a channel to carry water across without wasting it. Each team builds a channel from foil, clay, and straws in a tray, then runs a fair test by pouring the same amount of water from the well cup and watching how much reaches the three crop cups. The tilt and the walls of the channel are the design decisions students control, and the water that reaches the crop cups is how they find out whether those decisions worked.
Activity Directions
- Before class, set up each tray with a well cup taped at one end and three crop cups spaced along the other end. Fill each team's well cup with the same amount of water so every test starts fair.
- Introduce the problem: carry water from the well to all three crop rows with the least spill. Write the two criteria on the board, reach all three rows and spill the least, and the limit, use only the parts in the kit.
- Teams sketch two different channel ideas, such as a foil trough with clay walls or a row of straws joined end to end. The two ideas must be different so there is something to compare.
- Teams build their first channel across the tray, shaping foil into a trough and using clay to raise the sides and set a gentle downhill tilt toward the crops.
- Teams run the fair test: pour the well cup slowly into the top of the channel and watch how much water reaches each crop cup and how much spills onto the tray. They mark the result on the handout.
- Teams empty the tray, build their second design, and pour the same amount of water again, so the only thing that changed is the channel shape.
- Teams compare the two tests and circle the design that reached more crop cups with less spill.
- End the activity when every team has tested both designs and chosen a winner. Gather the class for the debrief.
- Debrief with two questions: "What did you keep the same to make the test fair?" and "What one change made your winning channel spill less?"
Student Handout
Mark your two tests on this chart. Write "a lot," "some," or "none" for spill.
| Design 1 | Design 2 | |
|---|---|---|
| Crop cups that got water (0 to 3) | ||
| How much spilled | ||
| Which is the winner? |
From Water for Schools (waterforschools.org). This material is in the public domain (CC0) and may be copied, edited, and shared freely.
Answer Key
- Question: What did teams keep the same to make the test fair? Answer: Teams kept the water amount, the well spot, and the three crop cups the same, and changed only the channel shape, so the test compared the two designs fairly.
- Question: Why does a gentle downhill tilt help the channel work? Answer: Water flows downhill on its own, so a gentle tilt toward the crops keeps the water moving to all three rows instead of pooling or running backward.
- Question: What is one change that usually cuts spill? Answer: Raising the channel walls with clay, sealing gaps between straws, or lowering the tilt so the water moves slower all cut spill; accept any change a team tied to its own test.
Differentiation
Support
Give these teams a foil trough that is already shaped, so their work goes into setting the tilt and sealing the sides. Provide a picture card showing "a lot," "some," and "none" of spill to make recording easier.
Extension
Challenge these teams to carry water to a fourth crop cup added farther away, using the same amount of water, and to explain what they changed so the water still reached the end. Ask them to predict which design a real farm would pick.
ELL supports
Pre-teach "channel," "well," "crop," and "spill" with labeled pictures and a quick demonstration pour. Provide sentence frames for the debrief, such as "We kept ___ the same" and "Our winner spilled less because ___."
Extensions
Show students a photo of real farm irrigation channels or furrows between crop rows and ask them to point out the same downhill tilt and raised sides they built. Connect the challenge to why farms in dry places design channels that lose as little water as possible.