Worksheet Grade 4 Science

Measuring How Far the Pennard Brook Bank Moved

A grade 4 worksheet using a year of post-to-bank measurements at three bends of a fictional brook, with subtraction items comparing erosion, cover, and deposition.

Grade: Grade 4
Subject: Science
Material: Worksheet
Time: 30 min
Prep: No prep
Materials: None

Standards

4-ESS2-1 NGSS

Make observations and/or measurements to provide evidence of the effects of weathering or the rate of erosion by water, ice, wind, or vegetation.

How this material aligns: Items 1 through 9 use repeated measurements from three marked posts as evidence of the rate of erosion by water, comparing a bare bank with a grassy bank.

All materials for 4-ESS2-1 →

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: Items 1, 2, 4, 5, and 8 are distance word problems in centimeters solved by subtraction, and items 3 and 6 compare two of those differences, which is the measurement word-problem work this standard names.

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 2026-09-04.

Objectives

Students will subtract measurements to find how far a brook bank moved between two dates.
Students will compare erosion at a bare bank and a grassy bank using numbers from a table.
Students will tell erosion apart from deposition by reading whether a measurement grew or shrank.

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.
Deposition: Deposition is when water vapor in the air turns directly into ice without ever becoming liquid first, the way frost forms on a cold window. It is the opposite of sublimation, where ice turns straight into vapor.

Also: bank, bend, ground cover

Teacher overview

A stream crew in the fictional town of Pennard set three posts along Pennard Brook and measured from each post to the edge of the bank four times in one year. The posts stand on flat ground well back from the water, so a shrinking measurement means the bank has been cut back toward the post, and a growing measurement means soil has been added on that side. The misconception this worksheet addresses is the belief that a brook only takes soil away. Post C sits on the inside of a bend where soil piles up, and its numbers grow, which gives students a concrete case of deposition sitting a few steps from a case of erosion. The three posts also differ in ground cover, so the data supports a comparison of bare dirt with thick grass.

Measuring How Far the Pennard Brook Bank Moved — Grade 4 Science

Name: ____________________________ Date: ______________

Student Worksheet

A crew set three posts along Pennard Brook. Four times in one year they measured from each post to the edge of the bank. All measurements are in centimeters.

Post A stands on the outside of a bend. The bank there is bare dirt.
Post B stands on a straight stretch. The bank there is covered with thick grass and shrubs.
Post C stands on the inside of the same bend as Post A. The bank there is sand and gravel.

Post	September	December	March	June
Post A	180 cm	162 cm	135 cm	120 cm
Post B	152 cm	149 cm	144 cm	140 cm
Post C	98 cm	101 cm	104 cm	106 cm

At Post A the bank edge was 180 cm from the post in September. In June it was 120 cm from the post. How many centimeters did the edge move?
At Post B the bank edge was 152 cm from the post in September. In June it was 140 cm from the post. How many centimeters did the edge move?
The Post A edge moved 60 cm. The Post B edge moved 12 cm. How many more centimeters did the Post A edge move?
At Post A the edge was 180 cm away in September and 162 cm away in December. How many centimeters did it move in the fall?
At Post A the edge was 162 cm away in December and 135 cm away in March. How many centimeters did it move in the winter?
The Post A edge moved 18 cm in the fall and 27 cm in the winter. In which season did it move more?
At Post C the edge was 98 cm from the post in September and 106 cm from the post in June. Did the brook carry soil away from Post C, or did it drop soil there?
At Post C the edge was 98 cm away in September and 106 cm away in June. How many centimeters did that edge move?
Post A has bare dirt. Post B has thick grass. Use one number from Post A and one number from Post B to explain why plants matter on a bank.
The crew can plant grass at only one post this year. Which post needs it most? Give one reason.

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: 60 cm.
Subtract the June measurement from the September one: 180 - 120 = 60 centimeters. The edge came 60 centimeters closer to the post, so the bank was cut back that far.
Answer: 12 cm.
152 - 140 = 12 centimeters. The grassy bank moved, but far less than the bare bank at Post A.
Answer: 48 cm.
60 - 12 = 48 centimeters more at Post A. Accept work that lines up both differences and subtracts, or a number line showing the gap.
Answer: 18 cm.
180 - 162 = 18 centimeters between the September and December visits.
Answer: 27 cm.
162 - 135 = 27 centimeters between the December and March visits.
Answer: The winter.
27 is greater than 18, so more soil moved in the winter. Students who compare the wrong pair of dates have usually used the September measurement in place of the December one.
Answer: The brook dropped soil there.
The measurement grew from 98 to 106 centimeters, so the edge moved away from the post. New sand and gravel piled up on the inside of the bend. This is deposition.
Answer: 8 cm.
106 - 98 = 8 centimeters. The edge moved away from the post rather than toward it.
Answer: Plants hold soil in place.
A full answer pairs two numbers, such as 60 centimeters of movement at bare Post A and 12 centimeters at grassy Post B, and states that the covered bank lost much less soil. Students may also point out that Post A sits on the outside of a bend, where the water pushes hardest, so the bend and the bare soil both help explain the difference. Accept this as stronger reasoning.
Answer: Post A.
Accept any answer naming Post A with a reason drawn from the table, such as its 60 centimeters of movement, the fact that its bank is bare, or the fact that it sits on the outside of a bend where the water pushes hardest.

Differentiation

Support

Give these students a copy of the table with the September and June columns highlighted and the other two columns covered, so items 1 through 3 need only one pair of numbers. Provide a subtraction frame with the larger number already written on top, and allow base-ten blocks or a number line for items 4 and 5. Read items 9 and 10 aloud and accept an oral answer.

Extension

Ask students to predict the Post A measurement for the following September and explain the reasoning behind the prediction, then state what could make the prediction wrong. A second task is to work out how many years it would take at this rate for the bank edge to reach Post A, and to explain why a crew would move the post before that happens.

ELL supports

Pre-teach bank, bend, bare, and edge with a labeled drawing of a brook seen from above, with the three posts and an arrow showing the flow. Provide a two-column word bank pairing "took soil away" with "erosion" and "dropped soil" with "deposition." Give sentence frames for items 9 and 10: "Post A moved ___ cm and Post B moved ___ cm, so plants ___." and "Post ___ needs grass most because ___."

Extensions

Have the class set two posts beside a puddle, a ditch, or a downspout outlet on school grounds and measure to the edge once a month, building a table with the same shape as this one. Students can also mark the three posts on a sketch of a bend and shade where they expect soil to be lost and where they expect it to build up.