Worksheet Grade 8 Careers & CTE

A Field Technician's Oxygen Data: Scatter Plots and Patterns

A grade 8 worksheet where students build and read a scatter plot of a technician's temperature and dissolved-oxygen readings, describing the association and an outlier.

Grade: Grade 8
Subject: Careers & CTE
Material: Worksheet
Time: 40 min
Prep: No prep
Materials: Graph paper or a printed grid

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: Items 2 through 5 have students construct a scatter plot of the technician's readings and describe the negative association and the single outlier, exactly the bivariate analysis this standard names.

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 2026-07-17.

Objectives

Students will construct a scatter plot from a water technician's paired temperature and dissolved-oxygen readings.
Students will describe the association and identify the outlier in the data.

Vocabulary

Dissolved oxygen: Dissolved oxygen is the oxygen gas mixed into water that fish and other underwater animals breathe. Cold, moving water holds more oxygen than warm, still water.

Also: scatter plot, association, outlier

Teacher overview

Field technicians who monitor streams record paired measurements all day, and reading those pairs as a pattern is a core grade 8 skill. This worksheet uses a fictional technician's log of water temperature and dissolved oxygen at a monitoring site to build and interpret a scatter plot. A common mistake this set targets is treating a single odd reading as proof the pattern is wrong; students learn to name it as an outlier instead.

A Field Technician's Oxygen Data: Scatter Plots and Patterns — Grade 8 Careers & CTE

Name: ____________________________ Date: ______________

Student Worksheet

Suppose a field technician records water temperature and dissolved oxygen at nine visits to a fictional creek monitoring site. Dissolved oxygen is the amount of oxygen in the water that fish need to breathe. The readings below are made up for this worksheet.

Visit	Temperature (°C)	Dissolved oxygen (mg/L)
1	8	11.2
2	11	10.1
3	13	9.6
4	16	8.7
5	18	8.0
6	21	7.1
7	24	6.0
8	27	4.6
9	12	6.3

Which quantity belongs on the x-axis, and which belongs on the y-axis, for this scatter plot?
Plot all nine points on graph paper, labeling both axes with their units.
Describe the association between temperature and dissolved oxygen for most of the points.
Cold water holds more oxygen than warm water. Explain how that fact matches the pattern you described.
One point does not fit the pattern. Give its visit number and its coordinates, and name it using the correct term.
Suggest one real reason a site might show unusually low oxygen for its temperature.
How much higher is the dissolved oxygen at the coldest visit (8°C) than at the warmest visit (27°C)? Show your subtraction.
Fish generally need dissolved oxygen above 5 mg/L. How many of the nine visits meet that benchmark?
Based on the overall pattern, would a visit at 30°C likely be above or below 6 mg/L? Explain.

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: Temperature on the x-axis and dissolved oxygen on the y-axis, because oxygen depends on temperature.
Answer: A scatter plot with nine points, temperature (8 to 27) on the x-axis in °C and dissolved oxygen (4.6 to 11.2) on the y-axis in mg/L, each axis labeled with its unit. Points 1 through 8 fall along a downward path; point 9 sits well below that path.
Answer: A negative (decreasing) association: as temperature rises, dissolved oxygen tends to fall.
Answer: Because cold water holds more oxygen, the coldest visits show the highest oxygen and the warmest visits show the lowest, which is exactly the downward pattern in the data.
Answer: Visit 9, at (12°C, 6.3 mg/L), is the outlier; at 12°C the pattern predicts oxygen near 9.6 to 10, so 6.3 is far below and does not fit.
Answer: Accept reasons such as pollution entering the water, decaying plants or algae using up oxygen, or a nearby discharge, any of which can lower oxygen below what the temperature alone would predict.
Answer: 6.6 mg/L. 11.2 mg/L − 4.6 mg/L = 6.6 mg/L.
Answer: 8 visits. Every reading except Visit 8 (4.6 mg/L) is above 5 mg/L, so 8 of the 9 visits meet the benchmark.
Answer: Below 6 mg/L. The pattern is decreasing, and the 27°C visit already reads 4.6 mg/L, so a hotter 30°C site would likely be lower still.

Differentiation

Support

Provide a pre-labeled grid with the axis units already written and the first three points already plotted, so students continue the plot rather than start it. Give the subtraction for item 7 set up as 11.2 − 4.6.

Extension

Ask students to estimate a "line of best fit" by eye, ignoring the outlier, and to use it to predict the dissolved oxygen at 14°C, explaining how they used the line.

ELL supports

Pre-teach "scatter plot," "dissolved oxygen," "association," and "outlier" with a simple picture of a downward point cloud and one stray point. Allow items 3 through 6 to be answered with short phrases and arrows on the plot.