Lab / experiment Grade 3 Science

Lumbry Bend's Water Wheel: A Grade 3 Pour-Height Fair Test

A grade 3 lab in which teams build a cork water wheel and test whether pouring one liter from a greater height makes the wheel spin more times in ten seconds.

Grade: Grade 3
Subject: Science
Material: Lab / experiment
Time: 60 min
Prep: Moderate prep
Materials: A large plastic tub or dish pan per team, One cork or thread spool per team, Six index-card blades cut to five centimeters per team, A wooden skewer or unsharpened pencil for the axle, Two plastic cups with V-notches cut in the rim, A one-liter pitcher marked in milliliters, A meter stick, A stopwatch or timer, Masking tape, A permanent marker, Scissors, Towels for spills, A bucket for emptying the tub

Standards

3-5-ETS1-3 NGSS

Plan and carry out fair tests in which variables are controlled and failure points are considered to identify aspects of a model or prototype that can be improved.

How this material aligns: Teams hold the water amount at one liter and change only the pour height, then use the spin counts and any wobbling failures to improve the wheel.

All materials for 3-5-ETS1-3 →

3.MD.A.2 Common Core Math

Measure and estimate liquid volumes and masses of objects using standard units of grams (g), kilograms (kg), and liters (l). Add, subtract, multiply, or divide to solve one-step word problems involving masses or volumes that are given in the same units, e.g., by using drawings (such as a beaker with a measurement scale) to represent the problem.

How this material aligns: Every trial begins with students measuring one liter in a marked pitcher and holding that amount equal across trials, which is the liquid-volume measuring half of this standard; the lab does not include its word-problem half.

All materials for 3.MD.A.2 →

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This material is in the public domain (CC0) and may be copied, edited, and shared freely, without attribution. Updated 2026-07-23.

Objectives

Students will build a small water wheel and set it up so it spins freely.
Students will run a fair test that changes only the pour height while the water stays at one liter.
Students will compare spin counts across three pour heights and name their controlled variables.

Vocabulary

Key words: water wheel, axle, blade, fair test, trial, pour height

Teacher overview

At a dam, water falls from the lake behind the wall down to a wheel below, and the spinning wheel drives a generator that makes electricity. This lab asks a single testable question about that arrangement: does pouring the same amount of water from a greater height make a small wheel spin more times? Teams build a cork wheel with index-card blades and run three trials at each of three pour heights, holding the water at one liter every time. The mill at Lumbry Bend named in the title is a fictional setting for the investigation, and the classroom wheel is a simple model rather than a working generator.

Lumbry Bend's Water Wheel: A Grade 3 Pour-Height Fair Test — Grade 3 Science

Name: ____________________________ Date: ______________

Procedure

Step 1 (safety). Water on the floor is slippery. Wipe up every spill right away. Do not drink any water used in this lab. Stand back from the tub while a partner pours.

Step 2 (build the wheel). Ask an adult to push the pointed skewer through the middle of the cork. Cut six blades from index cards. Tape the blades around the cork. Space them evenly all the way around.

Step 3 (build the stand). Cut a small V-notch in the rim of each cup. Set both cups right side up in the tub, a little less than a skewer-length apart. Rest the ends of the skewer in the two notches. Spin the wheel with one finger. It must spin freely before you go on.

Step 4 (mark one blade). Draw a dot on one blade with the marker. You will count the times that dot passes the top.

Step 5 (set the water amount). Fill the pitcher to the one-liter mark. Check the mark at eye level. Every trial uses one liter. This is the thing you keep the same.

Step 6 (set the pour height). Hold the spout of the pitcher 10 cm above the top blade. Use the meter stick to check the height. This is the one thing you will change later.

Step 7 (run the first trial). Give each person a job. One partner pours the liter in a steady stream. One partner counts the spins for 10 seconds. One partner runs the timer and calls "stop." Write the count in the table. Then empty the tub into a bucket. Do this after every trial so the wheel never touches standing water.

Step 8 (repeat at the same height). Run two more trials at 10 cm. Use one liter each time. Pour the same way each time.

Step 9 (change only the height). Now run three trials with the spout 30 cm above the top blade. Then run three more at 50 cm. Keep the water at one liter for all of them.

Step 10 (watch for failure points). Stop if the skewer jumps out of a notch. Stop if a blade bends flat or falls off. Fix the problem, then run that trial again. Write down what went wrong.

Data & Analysis

Pour height	Spins in 10 seconds, trial 1	Spins in 10 seconds, trial 2	Spins in 10 seconds, trial 3
10 cm
30 cm
50 cm

How many spins did your wheel make at 10 cm on trial 1?
Which pour height gave your wheel the most spins?
Take your highest spin count and your lowest spin count. How many more spins was the highest one?
You used one liter of water in every trial. Why did that amount have to stay the same?
Name one other thing you kept the same in every trial.
Did any trial fail? Tell what went wrong and what your team changed.
A dam sends water down a drop to a wheel. Use your spin counts. Should that drop be tall or short? Tell why.

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

Answer Key

Answer: Answers will vary by team. Accept any whole number the team actually recorded for the first trial at 10 cm. Classroom cork wheels commonly land somewhere between 3 and 15 spins in 10 seconds, so a count far outside that range is worth a second look at the setup.
Answer: Usually 50 cm. Accept whichever height the team's own table shows as highest. Water falling farther arrives faster and pushes the blades harder, so the tallest pour normally wins, though a wobbly stand can flip the result.
Answer: Answers will vary by team. Accept any difference that matches the team's own table when the lowest count is subtracted from the highest count. Check the subtraction rather than the size of the number.
Answer: To keep the test fair. Accept any answer explaining that a bigger pour would push the wheel more on its own, so the team could not tell whether the height or the extra water caused the change.
Answer: Accept any real control from the setup, including the same wheel, the same six blades, the same tub, the same steady pouring speed, the same 10-second count, or the same person doing the pouring.
Answer: Accept any failure the team recorded, such as the skewer jumping out of a notch, a blade bending flat, tape coming loose, or the wheel rubbing on a cup. Accept any repair that made the wheel spin freely again, and accept "no failures" from a team whose setup held together.
Answer: Tall. Accept any answer that uses the team's own counts to argue that a taller drop turned the wheel more times. A team whose data came out the other way should be credited for arguing from what they measured, with a note about what may have gone wrong.

Differentiation

Support

Build the cork wheels and the notched cup stands ahead of time so these students begin at Step 5 with a working setup. Give them a counting card with 20 printed boxes to check off one at a time as the dot passes, and reduce the test to two heights, 10 cm and 50 cm, with two trials each.

Extension

Ask students to run a second fair test that holds the pour height at 50 cm and changes only the number of blades, using three blades, six blades, and nine blades. They should predict the result first, keep the water at one liter, and explain which of the two tests told them more about how to improve the wheel.

ELL supports

Pre-teach "blade," "axle," "spin," and "pour" by turning a completed wheel by hand and naming each part as students touch it. Post a picture strip of the ten steps at each station. Provide the frames "At ___ cm the wheel spun ___ times" and "We kept ___ the same every time."