Lab / experiment Grade 4 Engineering & Design
Archimedes Screw Pump Lift: A Grade 4 Crank-Powered Water Lab
A grade 4 lab where students build a hand-cranked spiral pump from tubing and a dowel, measure how many cups of water it lifts per crank turn, and predict a larger total.
Objectives
- Students will build a hand-cranked screw pump and use it to lift water from a low tub to a catch cup.
- Students will measure and record how many cups of water the pump lifts for a set number of crank turns.
- Students will use a rate from a sample data set to predict the water lifted after a larger number of turns.
Vocabulary
- Pump
- A pump is a machine that adds energy to water to move it or push it uphill, doing the job gravity cannot do on its own. Water systems use many different kinds of pumps to move water from wells, through treatment, and out to customers.
Teacher overview
Water does not climb uphill on its own, which is exactly why every water system, from a well on a farm to a city's distribution network, relies on pumps to add the energy water needs to move upward. In this lab, groups build a simple hand-cranked screw pump, an old design that lifts water by spiraling it upward inside a turning tube, and measure how many cups of water it lifts for a set number of crank turns. A common misconception this lab addresses directly: students often think a pump only pushes water from behind, when a screw pump instead traps pockets of water inside its spiral and carries them physically upward as the whole tube turns, converting the turning motion of an arm into the upward motion of the water itself.
Procedure
Step 1 (build the screw, 15 min): Tape one end of the clear tubing near the top of the dowel. Wind the tubing around the dowel in a loose spiral, from top to bottom. Tape it in place every few inches so it holds its shape. Leave both ends of the tubing open.
Step 2 (set up the tub, 5 min): Place the bottom end of the tubing into the tub of water. Prop or hold the dowel at a tilt, about halfway between flat and upright. Keep the bottom end low in the water. Keep the top end higher, over the catch cup.
Step 3 (safety note): Use only clean tap water for this lab. Do not drink any water from the setup. Wipe up spills right away so the floor does not get slippery.
Step 4 (first trial, 8 min): Have one student turn the dowel steadily, like a crank. Keep turning until water first spills out the top, then empty the catch cup and start counting. Count 10 full turns at a slow, even pace. Empty the catch cup into the measuring cup. Record how many cups of water you collected in the data table.
Step 5 (second and third trials, 12 min): Empty the catch cup and put it back under the tube. Repeat the same steady turning for 20 turns. Then repeat it again for 30 turns. Record the cups collected after each trial.
Step 6 (class data check, 10 min): Compare each group's three trial results as a class. If a group's pump did not lift any water on a trial, check two things: is the tubing kinked, and does the bottom end stay fully underwater? Fix any problem and repeat that trial once before moving on.
Data & Analysis
Record your group's results in a table like this one:
| Trial | Number of crank turns | Cups of water collected |
|---|---|---|
| 1 | 10 | |
| 2 | 20 | |
| 3 | 30 |
Sample class data, for use in question 3 only: one class recorded 3 cups after 10 turns, 6 cups after 20 turns, and 9 cups after 30 turns.
Look at your own group's data. How many cups did your pump collect after 10 turns? After 30 turns?
Compare your three totals. Is your 20-turn total about double your 10-turn total? Is your 30-turn total about triple it? What does that pattern tell you about how steadily your pump lifted water?
Look at the sample class data above: 3 cups after 10 turns, 6 cups after 20 turns, and 9 cups after 30 turns. Predict how many cups would be collected after 50 turns if the same steady rate continued.
What form of energy did you put into the crank? What happened to that energy as the water rose through the spiral tube?
Why might it be hard for a student to turn the crank at a perfectly steady rate for a whole trial? How could an uneven turning speed change your group's results compared to the sample data?
Real water utilities use large motor-driven pumps instead of a hand crank. These pumps lift far more water than any person could turn by hand. Based on your results, explain why a hand-cranked screw pump would not work for supplying an entire town.
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 vary based on each group's own measurements.
Accept any pair of values the group actually recorded; the 30-turn value should be larger than the 10-turn value if the pump worked consistently across the trial.Answer: The totals should roughly double from 10 to 20 turns and triple from 10 to 30 turns.
A doubling-and-tripling pattern means the pump lifted water at a steady pace across the trial. Accept some variation, since turning speed by hand is rarely perfectly even, but the pattern should be visible for full credit. If the pattern breaks down, students should suggest a reason, such as a tiring arm, a change in tilt, or a tube that was not yet full of water when the first trial began.Answer: 15 cups.
Fifty turns is five times 10 turns, so the pump should collect five times as many cups as it did in 10 turns: 5 x 3 cups = 15 cups. Students can check the answer against the sample data pattern, which grows by 3 cups for every 10 turns.Answer: The motion energy from a student's turning arm became the motion energy of the water rising through the spiral tube. Accept any answer that names the arm's turning or mechanical energy as the input and the water's upward motion as the result, since this is the energy conversion the device performs. Also accept answers that say the energy is stored in the water because it has been lifted higher.
Answer: Turning by hand naturally speeds up and slows down, and a student's arm tires over a longer trial, so an uneven turning speed can make a group's own rate lower or less consistent than the clean, steady sample data. Accept any answer connecting inconsistent hand speed to a less steady or lower rate of water collected.
Answer: A hand-cranked pump can only turn as fast, and for as long, as one person's arm allows, while a town needs a steady, continuous supply of water for many hours every day without anyone resting. Accept any answer that connects human limits (fatigue, speed, needing rest) to the much larger and more constant water demand of an entire town, which is why real systems use motor-driven pumps instead.
Differentiation
Support (below grade level)
Pre-build one demonstration screw pump as a class before groups build their own, and provide a data table with only two trials (10 and 30 turns) instead of three to reduce the amount of counting and recording required.
Extension (above grade level)
Have groups test a second variable, such as tilting the dowel more steeply or more gently, and compare the new cups-per-turn rate to their original trial, explaining which tilt seemed to lift water more efficiently and why that might be true.
ELL supports
Demonstrate each procedure step once for the whole class before groups begin, using gestures for "turn," "tilt," and "collect." Allow groups to record trial results using numbers alone in the data table without written sentences, saving full sentences for the discussion questions with partner support.