Lab / experiment Grade 3 Engineering & Design

Barleyford Slope Ground Covers: A Grade 3 Fair Test

A grade 3 tray investigation comparing bare soil, a grass mat, and wood chips on a tilted slope, then adding a stone row and retesting the best cover.

Grade: Grade 3
Subject: Engineering & Design
Material: Lab / experiment
Time: 60 min
Prep: Moderate prep
Materials: 3 shallow trays or foil baking pans per team, Dry soil or potting mix, about 2 cups per tray, 1 piece of grass sod or a green scouring pad, cut to fit one tray, Wood chips or shredded paper, about 1 cup, 1 measuring cup marked in milliliters per team, Water, about 800 milliliters per team, 3 clear plastic cups per team to catch runoff, 1 book or block per tray to tilt it, About 12 small stones per team, 1 stopwatch or timer per team, Paper towels and a tray liner for spills, Newspaper to cover each table, Aprons or old shirts

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: Every tray gets the same 200 milliliters poured from the same height, only the cover changes, and Round 2 adds a stone row to the best cover, the controlled fair test and prototype improvement this standard names.

All materials for 3-5-ETS1-3 →

3-ESS3-1 NGSS

Make a claim about the merit of a design solution that reduces the impacts of a weather-related hazard.

How this material aligns: Question 8 asks students to recommend one ground cover for the real school slope and back it with their own muddiness data, the claim about a design solution for a rain hazard this standard requires.

All materials for 3-ESS3-1 →

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This material is in the public domain (CC0) and may be copied, edited, and shared freely, without attribution. Updated 2026-09-23.

Objectives

Students will pour the same amount of water on three covers to run a fair test.
Students will rate runoff muddiness on a shared 0 to 3 scale.
Students will add one change to the best cover and retest it.

Vocabulary

Key words: runoff, cover, slope, fair test

Teacher overview

The investigation question is which ground cover keeps the most soil on a slope when heavy rain falls, and the setting is a fictional bare slope beside the parking lot at Barleyford School, where brown water crosses the walkway after every storm. Teams pour the same measured water onto three tilted trays holding bare soil, a grass mat, and wood chips, catch the runoff, and rate how muddy each cup looks, then improve the winning cover and test it again. The classroom rating is a simple comparison by eye and is not an official measurement of water quality. Many students expect the cover that soaks up the most water to win and are surprised that a cover can help mainly by taking the hit of the falling drops, so it is worth asking before Round 1 what the cover is actually protecting the soil from.

Barleyford Slope Ground Covers: A Grade 3 Fair Test — Grade 3 Engineering & Design

Name: ____________________________ Date: ______________

Procedure

Stay safe. Put on an apron or an old shirt. Cover your table with newspaper. Do not drink any of the water in this lab. Wash your hands when you finish.

Fill the three trays. Put about 2 cups of dry soil in each tray. Pat the soil flat. All three trays must start with the same amount of soil.

Add the covers. Label the trays 1, 2, and 3. Tray 1 stays bare. Lay the grass mat on Tray 2. Spread wood chips over Tray 3.

Tilt the trays. Rest one end of each tray on a book so that end sits higher. Use books of the same thickness for all three trays, so every tray sits at the same tilt. Ask an adult for help if a tray slides. Put a clear cup under the low end of each tray to catch the runoff.

Pour the first test. Measure 200 milliliters of water. Hold the cup about 10 centimeters above the high end of Tray 1. Pour slowly and steadily. Start the timer as you begin to pour. Stop it when the water stops dripping into the cup. Write the time in the table.

Rate the runoff. Look at the cup and give it a muddiness number. A 0 means clear. A 1 means a little cloudy. A 2 means cloudy. A 3 means very muddy. Write the number in the table.

Test the other two trays. Do the same pour and the same rating for Tray 2 and Tray 3. Use 200 milliliters each time. Hold the cup at the same height each time. The cover is the only thing that changes.

Pick your best cover. Look at your three muddiness numbers. The tray with the lowest number holds your best cover.

Improve it and test again. Lay a row of about 12 small stones across the low end of the best tray. Change nothing else. Pour 200 milliliters from the same height, time it, and give the new cup a muddiness number.

Clean up. Wipe up spilled water right away so no one slips. Empty the cups into a sink, not onto the floor.

Data & Analysis

Copy this table and fill it in as you work.

Tray	Cover	Water poured
1	Bare soil	200 milliliters
2	Grass mat	200 milliliters
3	Wood chips	200 milliliters
Best tray, Round 2	Best cover plus a stone row	200 milliliters

Which tray gave the muddiest runoff?
What muddiness number did you give that tray?
Which tray gave the clearest runoff?
Why did every tray get the same 200 milliliters of water?
Which cover kept the most soil on the slope? Use your muddiness numbers in your reason.
In Round 2 you added a row of stones to your best cover. Did the muddiness number go down, go up, or stay the same?
Name one thing that went wrong or nearly went wrong in a test. Tell how it could change your result.
Barleyford School must pick one cover for the real slope. Which cover do you recommend? 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: Tray 1, the bare soil, in almost every run. Accept a different tray if the team's own record supports it, and use that record in the debrief to hunt for what went wrong.
Answer: Accept the number the team recorded, usually a 2 or a 3 for bare soil. The number must match the table, not a guess written afterwards.
Answer: Accept whichever tray the team recorded, most often Tray 2 or Tray 3. Both covers usually beat bare soil, and which one wins depends on how thickly the chips were spread.
Answer: Accept any answer saying the test would not be fair otherwise. Pouring 200 milliliters on every tray means the only thing that changed between trays is the cover, so a difference in the cups comes from the cover.
Answer: Accept the cover with the lowest muddiness number in the team's own table, provided the reason names both numbers being compared. A reason that only says one cover looked better should be sent back for the numbers.
Answer: Accept down, up, or the same, matching the team's two recorded numbers. The number usually goes down a little, because the stones slow the water and some soil settles before it reaches the cup.
Answer: Accept any honest problem, such as a tray slipping off the book, water poured too fast, uneven soil, or chips washing into the cup. The answer must say how that problem could change the muddiness number.
Answer: Accept any of the three covers, or the best cover plus the stone row, provided the recommendation names a muddiness number from the team's table as the reason. Recommendations with no number from the data are incomplete.

Differentiation

Support

Set up the three trays in advance for these teams so the work starts at the pouring step, and give them a printed muddiness card with four shaded circles they can hold beside the cup. Assign one student to pour and one to call out the timer so no one tracks two jobs at once.

Extension

Ask these teams to run each tray twice and compare the two runs before answering question 5, then to explain what a second run tells them that a single run cannot. Have them design a second improvement for their best cover and predict, in writing, what the muddiness number will do.

ELL supports

Pre-teach slope, runoff, cover, and muddy with the trays in front of the class and a hand motion for water running downhill. Provide the frames "Tray ___ was the muddiest" and "I recommend ___ because my number was ___." Allow the muddiness rating to be shown by pointing at a shaded card before it is written.

Extensions

Take the class to a real bare slope, a bare patch under a downspout, or a worn path on the school grounds and look for the same signs of moving soil, such as small channels and a fan of dirt at the bottom. Teams can mark on a sketch where they would place their winning cover and where a stone row would sit.