Lesson plan Grade 5 Science

Tessington Gorge Dam: Modeling a River Before and After

A 55-minute grade 5 lesson where teams run a sand stream table twice, once open and once dammed, to model how a dam changes a river and its sediment.

Grade: Grade 5
Subject: Science
Material: Lesson plan
Time: 55 min
Prep: Moderate prep
Materials: Plastic tub or baking tray about 12 by 18 inches, one per team, 4 cups of play sand or clean soil per team, Pitcher of water, about 1 liter per run, Piece of stiff foam board or cardboard, 4 inches by 6 inches, per team, Two books or blocks to prop up one end of each tray, Plastic cup with a small hole in the bottom, one per team, Bucket and towels for cleanup, Clear cup and spoon for the teacher's hook demonstration, Printed student handout, one per student

Standards

5-ESS2-1 NGSS

Develop a model using an example to describe ways the geosphere, biosphere, hydrosphere, and/or atmosphere interact.

How this material aligns: Teams build and run a sand-and-water model showing how the hydrosphere and the geosphere interact when a dam slows a river and drops its sediment behind the wall.

All materials for 5-ESS2-1 →

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

Objectives

Students will build a model that shows water and land interacting in a river valley.
Students will compare a river channel before and after a dam is added to the model.
Students will explain where sediment collects when a dam slows moving water.

Vocabulary

Dam: A strong wall built across a river to hold back water. Dams store water for people and farms, help prevent floods, and can make electricity.
Reservoir: A human-made lake, usually created by a dam, that stores water for later. Reservoirs supply cities and farms and help control floods.

Also: sediment, channel, model

Teacher overview

The fictional town of Tessington sits below a narrow gorge where the Wenlock River drops out of the hills. When engineers put a dam across a gorge like that one, they change two Earth systems at once: the water slows and spreads into a reservoir, and the sand and grit the river was carrying settle to the bottom instead of moving downstream. This lesson has teams run the same sand tray twice, first with an open channel and then with a foam dam wedged across it, so the two results sit side by side. A common misconception in this lesson is that a dam only holds water back. The sediment the river was carrying also drops out in the still water behind the wall, which is why the water leaving a dam usually runs clearer than the water arriving.

Procedure

Hook (5 min): Show students a cup of water with a spoonful of sand stirred into it. Ask what happens to the sand if the cup sits still for a minute, then ask what happens to sand carried by a river when the river slows down. Hold the class to a prediction before any water is poured.

Setup (10 min): Teams spread 4 cups of sand along one half of the tray and use a finger to carve a channel from the high end to the low end. Prop the high end of the tray on two books so the channel slopes. Set the tray's low end over a bucket or a towel. Remind students that the sand stands for the geosphere and the water they pour stands for the hydrosphere.

Run 1, open channel (10 min): One student pours water slowly from the cup with the hole in the bottom into the top of the channel while teammates watch the whole length of the tray. Teams sketch the channel afterward and note where sand moved, where the water ran fastest, and how cloudy the water looked at the bottom end.

Run 2, with the dam (10 min): Teams smooth the sand back into place and wedge the foam board across the middle of the channel, pressing sand against both sides so water cannot slip past the edges. They pour the same amount of water into the top of the channel in the same way. Teams watch the pool build behind the board, then watch what comes over or around it.

Handout and drawing (12 min): Students answer the five handout questions and label their two sketches. Circulate and ask at least three teams to point to the exact spot in the tray where sand collected during Run 2. Use their answers as the formative check: any team that cannot point to the pool behind the dam should be sent back to the tray to pour one more cup of water and watch again.

Debrief (8 min): Bring the class together and take one observation from each team. Close by explaining that in the town of Tessington, crews measure how much sediment has piled up behind the real dam every few years, because a reservoir that fills with sand holds less and less water over time.

Tessington Gorge Dam: Modeling a River Before and After — Grade 5 Science

Name: ____________________________ Date: ______________

Student Handout

Your team runs the tray twice. Write what you see each time.

In Run 1, with no dam in the tray, describe the path the water took from the top of the channel to the bottom. Tell where the water moved sand.
In Run 2, with the foam dam in the tray, describe what happened to the water right behind the dam.
Compare the sand behind the dam in Run 2 to the same spot in Run 1. What is different?
Compare how cloudy the water looked below the dam in Run 2 to how cloudy it looked at the bottom of the tray in Run 1.
Your tray is a model of the Wenlock River above the town of Tessington. Name one thing your tray shows well and one thing about a real river that your tray cannot show.

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 water ran down the carved channel and picked up sand along the way. Accept any description that has the water following the slope from the high end to the low end and moving sand from the upper channel toward the bottom of the tray.
Answer: The water piled up behind the dam and spread out into a pool, then slowed down. Accept any answer describing a pool, a lake, or a reservoir forming behind the board.
Answer: Sand collected in a layer behind the dam in Run 2, because the pooled water slowed down and could no longer carry the grains. In Run 1 that same sand kept moving down the channel.
Answer: The water below the dam in Run 2 looked clearer than the water at the bottom of the tray in Run 1, because much of the sand dropped out in the pool. Accept "clearer," "less muddy," or a team's own comparison as long as it matches what they recorded.
Answer: The tray shows the pool forming and the sediment settling behind the wall. It cannot show fish, plants, rain falling across the whole watershed, or the size and strength of a real river. Accept any reasonable pair of strengths and limits.

Differentiation

Support

Pre-carve the channel in these teams' trays and mark the dam's position with a line so the setup step does not use up their observation time. Give them a two-column recording sheet labeled "Run 1" and "Run 2" with the sketch boxes already drawn.

Extension

Have these teams run the tray a third time with the foam dam moved higher up the channel, closer to the head of the model gorge above the town of Tessington, and describe how the size and shape of the pool changed. Ask them to explain which placement would store more water.

ELL supports

Pre-teach "dam," "reservoir," "sediment," and "channel" by pointing to each one in the tray as the class says the word. Allow students to answer questions 1 through 4 with labeled drawings and short phrases instead of full sentences.

Extensions

Ask students to find a photograph of a real dam and reservoir in an atlas or a library book and describe where the sediment in that reservoir most likely settles. Teams can also test what happens when the foam dam is pulled out suddenly while the pool is full, which models a dam failure and shows why engineers inspect dams on a schedule.