Lab / experiment Grade 4 Engineering & Design

Claypool School's Drain Slope: A Sand-and-Water Fair Test

A grade 4 lab where groups tilt a foil channel to three heights, time the water, and measure the sand left behind to find the slope that carries grit away.

Grade: Grade 4
Subject: Engineering & Design
Material: Lab / experiment
Time: 55 min
Prep: Moderate prep
Materials: Heavy-duty aluminum foil, about 2 feet long, per group, Cardboard strip about 2 feet long to hold the foil channel straight, per group, Books or blocks for propping up one end of the channel, Ruler marked in inches and centimeters, per group, Measuring cup, per group, Dry sand, about 6 tablespoons per group, Tablespoon for measuring sand, per group, Stopwatch or timer, per group, Dishpan or bucket to catch the water, per group, Towels for spills

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: Groups change only the rise of the channel across three trials, hold the water and sand amounts constant, and study the spill-over failure point in question 6.

All materials for 3-5-ETS1-3 →

4.MD.A.2 Common Core Math

Use the four operations to solve word problems involving distances, intervals of time, liquid volumes, masses of objects, and money, including problems involving simple fractions or decimals, and problems that require expressing measurements given in a larger unit in terms of a smaller unit.

How this material aligns: Questions 1 and 2 read measured times in seconds and sand-trail lengths in centimeters out of the group's own data table, and question 3 subtracts the shortest recorded time from the longest.

All materials for 4.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 channel and run a fair test that changes only the rise of one end.
Students will time the water and measure the sand left in the channel for three different rises.
Students will use their own data to recommend a slope for a school drain pipe.

Vocabulary

Key words: slope, rise, grit, channel, fair test

Teacher overview

The drain pipes that carry used water away from a school are never laid flat, because water sitting in a level pipe drops its grit and slowly plugs the line. Crews at the fictional Claypool School are replacing one such pipe and have asked how much the new one should tilt. In this lab, groups build a foil channel, prop one end to three different heights, and pour the same mix of water and sand down it each time, timing the flow and measuring how much sand stays behind. The investigation is a fair test in which only one variable changes, the rise of the channel, and the failure point to watch for on the steepest trial is water spilling over the side.

Claypool School's Drain Slope: A Sand-and-Water Fair Test — Grade 4 Engineering & Design

Name: ____________________________ Date: ______________

Procedure

Step 1 (build the channel, 10 min): Lay the cardboard strip flat. Center the foil on top of it and fold both long edges of the foil upward about one inch to make a U-shaped channel with a flat bottom. Press the folds firmly so the sides stand up on their own.

Step 2 (set up the first trial, 5 min): Put the low end of the channel over the dishpan. Stack books under the high end until the ruler shows a rise of 2 inches above the table. Keep the channel straight, with no dips in the middle.

Step 3 (safety note): Use only clean tap water and clean play sand. Do not taste or drink anything used in this lab. Wipe up spills right away so no one slips, and keep the dishpan on the floor or on a low chair so nothing tips over.

Step 4 (trial 1, 8 min): Measure 1 cup of water and stir 2 tablespoons of sand into it. Start the timer and pour the whole cup at the top of the channel in one steady pour. Stop the timer when water stops running into the dishpan. Write the time in the data table. Then use the ruler to measure, in centimeters, how long the trail of leftover sand is in the channel, and write that down too.

Step 5 (trials 2 and 3, 15 min): Rinse and dry the channel. Raise the high end to a rise of 4 inches and repeat trial 1 exactly, using 1 cup of water and 2 tablespoons of sand again. Then rinse the channel again, raise the high end to a rise of 6 inches, and run the third trial the same way. Record the time and the sand trail length after each trial.

Step 6 (keep the test fair, during trials): Change only the rise between trials. Use the same channel, the same 1 cup of water, the same 2 tablespoons of sand, and the same pouring spot every time. If the water splashes out of the channel, say so in your notes and run that trial again.

Step 7 (clean up, 5 min): Pour the used water and sand into the sink strainer or a waste bucket as your teacher directs. Flatten and recycle the foil, and dry the ruler and the measuring cup.

Data & Analysis

Record your group's three trials in a table like this one:

Trial	Rise at the high end (inches)	Time until the water stops running into the dishpan (seconds)	Length of the sand trail left behind (cm)
1	2
2	4
3	6

Which trial had the shortest time? Write the rise and the time from your table.
Which trial left the shortest sand trail? Write the rise and the length from your table.
Subtract your shortest time from your longest time. How many seconds apart were they?
Look at all three trials in order. As the rise got bigger, what happened to the sand left in the channel?
Name one thing you kept the same in every trial. Why does keeping it the same make your test fair?
In one group's third trial, water splashed over the side of the channel before it reached the dishpan. What could that group change so the water stays inside the channel next time?
A school drain pipe is laid on a slope so that water carries grit away instead of leaving it in the pipe. Using your table, would you tell the Claypool crew to use more slope or less slope? Give one reason from your own data.

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: The 6-inch rise, with the shortest recorded time. Accept whichever trial the group actually timed as fastest, as long as the rise and the time match its own table; most groups find that the steepest channel drains fastest.
Answer: The 6-inch rise, with the shortest sand trail. Accept the trial the group measured as leaving the least sand, with the rise and the length copied correctly from its table.
Answer: The difference between the group's two times. Check that the student subtracted the smaller time from the larger one and labeled the answer in seconds.
Answer: Less sand stayed in the channel as the rise got bigger. Accept any answer that describes the sand trail growing shorter, or the channel looking cleaner, as the channel got steeper. If a group's data shows no clear pattern, accept that report along with a reason, such as an uneven pour.
Answer: The amount of water, the amount of sand, the channel itself, or the pouring spot. Keeping everything but the rise the same means any change in the results came from the rise, which is what the test is meant to measure.
Answer: Pour more slowly, fold the channel sides higher, or use a smaller rise. Accept any change that keeps the water inside the channel, as long as the student names one specific thing to change.
Answer: More slope, because the steeper trials moved more sand out of the channel. Accept a recommendation for less slope only if the group's own data shows a shorter sand trail at a smaller rise, and accept a middle recommendation supported by data showing splashing at the steepest rise.

Differentiation

Support

Pre-fold one channel for these groups and mark the book stacks for the 2-inch, 4-inch, and 6-inch rises ahead of time, so setup does not eat the testing minutes. Give a data table with the rise column already filled in and a sentence starter for question 4: "When the rise got bigger, the sand ___."

Extension

Have these groups run a fourth trial at a rise of 8 inches and decide whether the extra steepness helped or caused a new problem, then write a short recommendation for Claypool that names both the best rise and the trouble that comes with going too steep.

ELL supports

Demonstrate one full trial for the class before groups begin, using gestures for "rise," "pour," and "left behind." Provide picture labels for the ruler, the measuring cup, and the tablespoon, and allow students to record the sand trail as a drawing with its measurement written beside it rather than in a sentence.

Extensions

Have groups test a second variable while holding the rise steady at 4 inches, such as pouring the same cup of water in one fast pour instead of a steady pour, and compare the sand left behind with their original trial. Ask them to explain which condition a real drain pipe is more likely to face during a heavy rain.