Worksheet Grade 8 Math

Dry Larch Valley Well Levels: A Groundwater Scatter Plot

A grade 8 worksheet where students build and read a scatter plot of yearly well depth-to-water, then describe the trend and spot an outlier year.

Grade: Grade 8
Subject: Math
Material: Worksheet
Time: 35 min
Prep: No prep
Materials: Graph paper or printed grid, Ruler

Standards

8.SP.A.1 Common Core Math

Construct and interpret scatter plots for bivariate measurement data to investigate patterns of association between two quantities, describing clustering, outliers, and positive, negative, linear, or nonlinear association.

How this material aligns: Students plot the paired year and depth-to-water data in item 1 and then describe positive association, identify the outlier year, and judge clustering in items 3, 4, and 10.

All materials for 8.SP.A.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 construct a scatter plot from a two-variable data table.
Students will describe the association shown and identify an outlier.

Vocabulary

Key words: scatter plot, association, outlier, trend

Teacher overview

When a well crew measures how far down the water sits each spring, the numbers over several years show how the aquifer is changing. This worksheet gives students eight years of "depth to water" readings from a fictional farming area, Dry Larch Valley, where depth to water means how many feet below the ground the water level lies. A larger depth means the water table has dropped. Students plot the data, name the trend, and find the one year that breaks the pattern. A common error is reading a rising depth as a rising water table; remind students that a bigger depth-to-water number means less water, not more.

Dry Larch Valley Well Levels: A Groundwater Scatter Plot — Grade 8 Math

Name: ____________________________ Date: ______________

Student Worksheet

The table shows Dry Larch Valley's spring depth-to-water readings, in feet below the ground.

Year	Depth to water (ft)
2016	40
2017	43
2018	46
2019	49
2020	39
2021	55
2022	58
2023	61

Plot the eight points on a scatter plot. Put the year on the horizontal axis and the depth to water on the vertical axis.
As the years go on, does the depth to water generally go up or down?
Is the association between year and depth to water positive or negative?
One year does not fit the pattern. Which year is the outlier?
The years just around the outlier read 49 and 55 feet, so the pattern near it is about 52 feet. Give the outlier's depth and how many feet below 52 it is.
From 2016 to 2023, how many feet did the depth to water change?
That change took how many years, and what is the average change per year?
If the average yearly change from item 7 continues, predict the depth to water in 2024.
A greater depth to water means the water table has fallen. Over these years, is the valley's water table rising or falling? Answer in one sentence.
Leaving out the outlier year, do the points sit close to a straight line or spread far from one?

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: A scatter plot with eight points. Years 2016 through 2023 run left to right on the horizontal axis, and depth to water from about 39 to 61 feet runs up the vertical axis; the point for 2020 sits well below the others.
Answer: Up. The depth to water generally increases from 40 feet in 2016 toward 61 feet in 2023.
Answer: Positive. As the year increases, the depth to water tends to increase, so the association is positive.
Answer: 2020. Its reading of 39 feet is much lower than the rising values around it.
Answer: 39 feet. It is 52 - 39 = 13 feet below the pattern value of about 52 feet.
Answer: 21 feet. From 40 feet in 2016 to 61 feet in 2023 is 61 - 40 = 21 feet.
Answer: 3 feet per year. The change of 21 feet took 2023 - 2016 = 7 years, and 21 ÷ 7 = 3 feet per year.
Answer: 64 feet. Add one more year of change: 61 + 3 = 64 feet.
Answer: Falling. The depth to water keeps growing over the years, which means the water table is dropping.
Answer: Close to a straight line. Except for the 2020 outlier, the points climb steadily and stay near a rising straight line.

Differentiation

Support

Provide a grid already labeled with the year and depth-to-water scales so students only place the eight points. Work item 6 together as a model of finding a change by subtracting, then let students finish items 7 and 8 on their own.

Extension

Ask students to draw a straight line that best follows the seven points other than the outlier, then use their line to estimate the depth to water in 2025 and explain why an estimate that far ahead is less certain.

ELL supports

Pre-teach "depth to water," "outlier," and "trend" with a simple side-view drawing of the ground, the well, and the water level. Provide sentence frames: "The association is ___ because as the year goes up, the depth goes ___," and "The outlier year is ___."