Lesson plan Grade 6 Engineering & Design

Cutter Hollow Erosion Barrier Design and Sediment Test

Teams model a hillside in a tray, measure sediment reaching a downstream cup, then design and test a barrier that reduces erosion for the fictional town of Cutter Hollow.

Grade: Grade 6
Subject: Engineering & Design
Material: Lesson plan
Time: 50 min
Prep: Moderate prep
Materials: 1 plastic tray or aluminum roasting pan per team, propped at one end to form a slope, 2 cups of play sand or loose potting soil per team, 1 small collection cup at the low end of the tray to represent the downstream town, About 1/4 cup of modeling clay per team, for building the barrier, 2 measuring cups of water per team (1 cup for the control test, 1 cup for the barrier test), A kitchen scale or balance, shared among teams, Paper towels for cleanup

Standards

MS-ETS1-2 NGSS

Evaluate competing design solutions using a systematic process to determine how well they meet the criteria and constraints of the problem.

How this material aligns: Teams compare their control test's sediment mass with their barrier test's sediment mass using a shared percent-reduction calculation, the systematic evaluation against success criteria this standard names directly.

All materials for MS-ETS1-2 →

MS-ESS3-3 NGSS

Apply scientific principles to design a method for monitoring and minimizing a human impact on the environment.

How this material aligns: The barrier design and test model a method for minimizing a human impact on the environment, soil eroded from a disturbed hillside and carried downstream, and the percent-reduction measurement monitors how well the method works.

All materials for MS-ESS3-3 →

6.RP.A.3 Common Core Math

Use ratio and rate reasoning to solve real-world and mathematical problems, e.g., by reasoning about tables of equivalent ratios, tape diagrams, double number line diagrams, or equations, including finding a percent of a quantity and converting measurement units.

How this material aligns: Every team applies the percent-reduction formula, before minus after divided by before times 100, to their own control and barrier test masses, finding a percent of a quantity from real measured data.

All materials for 6.RP.A.3 →

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This material is in the public domain (CC0) and may be copied, edited, and shared freely, without attribution. Updated 2026-07-16.

Objectives

Students will run a control test measuring sediment reaching a downstream point with no barrier in place.
Students will design and build a small barrier intended to reduce sediment reaching the downstream point.
Students will calculate the percent reduction in sediment mass between the control test and the barrier test.

Vocabulary

Erosion: Erosion is the wearing away and carrying off of soil and rock by moving water, wind, or ice. Fast-moving stormwater can strip soil from bare ground and stream banks.

Also: sediment, barrier, runoff, percent reduction

Teacher overview

The fictional town of Cutter Hollow sits below a sloped hillside that erodes heavily during storms, sending soil into the town's stormwater system. This lesson has student teams model that hillside in a tray, measure how much sediment reaches a downstream "town" cup with no barrier in place, then design and test a small barrier meant to slow the water and catch sediment before it arrives. A common misconception in this lesson is that any barrier automatically helps; teams that place their barrier too high on the slope, where the water is still moving slowly, often see little improvement, which is the kind of result the percent-reduction calculation will show.

Procedure

Hook (5 min): Ask students what they think happens to loose soil on a hillside during a heavy rainstorm, and where they think that soil ends up. Take a few predictions without confirming an answer.

Direct instruction (10 min): Explain the setup: each team's tray represents a hillside sloping down toward a town. Introduce the percent-reduction formula teams will use to judge their barrier's success: percent reduction equals sediment before minus sediment after, divided by sediment before, times 100. Work a sample calculation as a class: if a control test collects 40 grams of sediment and a barrier test collects 10 grams, the percent reduction is (40 minus 10) divided by 40, times 100, which equals 30 divided by 40 times 100, or 75 percent.

Control test (10 min): Teams first weigh the empty collection cup. With no barrier in the tray, teams pour 1 measured cup of water slowly at the top of the slope and let it run down into the collection cup at the bottom. Teams pour off the water carefully, weigh the cup with its sediment, subtract the empty cup's mass, and record the result as their "before" mass in grams.

Design and build barrier (10 min): Teams empty and reset their tray, then build a small barrier partway down the slope using modeling clay, positioning it where they predict it will slow the water most effectively before sediment reaches the collection cup.

Barrier test and measure (10 min): Teams pour a second measured cup of water at the top of the slope, let it flow past their barrier and into the collection cup, then weigh the new sediment mass the same way and record it as their "after" mass in grams. Teams calculate their own percent reduction using the formula from direct instruction.

Closure and exit ticket (5 min): Ask the class why a barrier placed near the top of the slope often reduced sediment less than one placed farther down. Then students answer individually: "A different team's control test collected 50 grams of sediment, and their barrier test collected 20 grams. What is their percent reduction?" Collect and scan responses before dismissal.

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: 75 percent. The sample calculation's before mass (40 g) minus after mass (10 g) is 30 g; 30 divided by 40, times 100, equals 75 percent reduction.
Exit ticket answer: 60 percent. (50 minus 20) divided by 50, times 100, equals 30 divided by 50 times 100, which is 60 percent reduction.
Discussion answer: A barrier placed too close to the top of the slope meets water before it has picked up much sediment and before it is moving quickly, so it slows very little sediment; a barrier placed farther down, where more sediment has already been picked up, often produces a larger percent reduction.

Differentiation

Support

Provide teams with a completed control-test example (40 grams before) and let them focus their planning time on barrier placement and shape rather than running their own control test from scratch, using the class example as their "before" number.

Extension

Ask teams to test their barrier a second time with double the water (2 cups instead of 1) and compare whether their percent reduction stays about the same, increases, or decreases, then explain one reason for what they observe.

ELL supports

Pre-teach "sediment," "erosion," "barrier," and "slope" with a simple diagram showing water flowing downhill, picking up soil, and being slowed by a barrier. Allow teams to record their before and after masses as numbers on a simple two-column chart instead of full sentences.

Extensions

Have students research, using only teacher-provided images, what a real check dam or sediment fence looks like at a construction site, and compare its placement and shape to the barrier design their team tested.