Water for Schools
Menu

Classroom activity Grade 4 Science

Lifting Water at Redbridge: Build a Model Waterwheel Pump

A grade 4 build activity where small groups construct a spinning paddle wheel that scoops and lifts water, then run a fair test comparing angled and flat paddle cups.

Objectives

  1. Students will build a paddle wheel that scoops and lifts water as it turns, converting motion energy into lifting work.
  2. Students will run a fair test comparing angled and flat paddle cups, timing and measuring how much water each design lifts.
  3. Students will explain how their model relates to real water pumps and hydroelectric dams.

Vocabulary

Turbine
A machine with blades that spin when water rushes past, like a high-tech waterwheel. Spinning turbines turn generators that make electricity.

Also: energy conversion, axle, paddle

Teacher overview

This is a small-group build activity for groups of three or four students, set at the fictional town of Redbridge, where the class is asked to model how an old-fashioned water-lifting wheel moves water uphill without an electric pump. Each group builds a spinning paddle wheel with small cups taped around its rim: as the wheel turns, each cup scoops water from a low basin, carries it up and over, and empties it into a raised catch-cup, converting the motion of turning the wheel into the work of lifting water against gravity. Turning the wheel by hand stands in for the motion energy that a real paddle wheel, water pump motor, or falling-water turbine converts into useful work.

Activity Directions

  1. Push the wooden skewer through the center of the cardboard circle so the circle can spin freely on the skewer, like an axle through a wheel.

  2. Tape 8 small paper cups evenly around the edge of the cardboard circle, with every cup opening facing the same direction (all turning the same way), so each cup can scoop water as the wheel spins.

  3. Rest the skewer's two ends across the tops of two supports, such as stacked books, so the wheel hangs freely above the tub, set up as the lower basin, with the wheel's bottom edge just touching the basin.

  4. Set the plastic cup in place as the upper catch-cup, positioned where the wheel's small paper cups tip over and empty as they reach the top of their turn.

  5. Pour the 2-cup pitcher of water into the lower basin.

  6. Turn the wheel by hand through one full turn to check that each small cup fills at the bottom and empties into the upper catch-cup at the top. If a cup does not scoop water or does not empty at the top, adjust its angle with a small piece of tape.

  7. Fair test: Time 30 seconds while one team member turns the wheel at a steady speed, counting how many small cups empty into the upper catch-cup. Measure the water collected with the ruler or measuring cup and record the amount. Repeat the same 30-second test with the cups re-taped flat instead of angled, keeping the turning speed and the 30-second timer exactly the same, so the only thing that changes between tests is the cup angle.

  8. Compare the two 30-second results as a group and record which design lifted more water.

The activity ends once every group has completed both 30-second tests (angled cups and flat cups) and recorded both results on their group's data sheet. Gather the class for the debrief once every group has finished.

From Water for Schools (waterforschools.org). This material is in the public domain (CC0) and may be copied, edited, and shared freely.

Answer Key

  1. Debrief question: Which design lifted more water in 30 seconds, the angled-cup wheel or the flat-cup wheel, and why? Answer: The angled-cup wheel.
    Angled cups scoop and hold water on the way up, while flat cups let water spill back out before reaching the top, so the angled design lifts more water in the same 30 seconds.

  2. Debrief question: Where does a real water treatment plant get the energy to lift water into a storage tower? Answer: Electric pump motors.
    Real distribution systems use electric motors to power pumps, unlike this model, which is turned by hand.

  3. Debrief question: Where does a dam get the energy to spin a turbine? Answer: The motion energy of falling water.
    Water falling through a dam turns a turbine directly, converting the water's own motion energy into electrical energy, the reverse of this activity's hand-turned wheel lifting water.

Differentiation

Support (below grade level)

Pre-tape the paddle cups at a working angle for the first test so the group can focus on timing and measuring, then let them re-tape the cups flat for the second test with a checklist showing each step in order.

Extension (above grade level)

Ask groups to test a third design using 4 cups instead of 8, spaced evenly around the wheel, and to predict before testing whether fewer cups will lift more or less water in the same 30 seconds than the original 8-cup design, then explain any difference between their prediction and their result.

ELL supports

Demonstrate steps 1 through 6 slowly in front of the whole class before groups begin, labeling axle, paddle, and catch-cup on the physical model as each part is added. Allow groups to record their fair-test results using a simple picture-and-number chart instead of full sentences.

Extensions

Show a photograph or video of a real hydroelectric dam's turbine, and ask students to point out which part of their model matches the turbine and which part matches the falling water that spins it.