Worksheet Grade 6 Science

Sedgemoor Reservoir: Temperature and Dissolved Oxygen Data

A grade 6 science worksheet where students summarize a fictional reservoir's oxygen data and link warm water to lower oxygen for fish.

Grade: Grade 6
Subject: Science
Material: Worksheet
Time: 30 min
Prep: No prep
Materials: None

Standards

6.SP.B.5 Common Core Math

Summarize numerical data sets in relation to their context, reporting the number of observations, describing the attribute measured, giving quantitative measures of center and variability, and relating the choice of measures to the shape of the distribution.

How this material aligns: Items 1, 2, 3, and 8 have students report the range, mean, and median of a dissolved oxygen data set and relate the center to the spread, as this standard requires.

All materials for 6.SP.B.5 →

MS-LS2-1 NGSS

Analyze and interpret data to provide evidence for the effects of resource availability on organisms and populations of organisms in an ecosystem.

How this material aligns: Items 5, 6, and 7 have students interpret the oxygen data as evidence that a resource's availability affects fish, the cause-and-effect analysis this standard requires.

All materials for MS-LS2-1 →

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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 find the range, mean, and median of a dissolved oxygen data set.
Students will describe how water temperature and dissolved oxygen are related and what that means for fish.

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: range, mean, median

Teacher overview

Dissolved oxygen is the oxygen gas mixed into water, and fish depend on it to breathe. Warm water holds less dissolved oxygen than cold water, so a lake's oxygen can change with the seasons. This worksheet gives students a year of surface readings from Sedgemoor Reservoir, a fictional reservoir, and asks them to summarize the data and explain what the pattern means for the fish that live there.

Sedgemoor Reservoir: Temperature and Dissolved Oxygen Data — Grade 6 Science

Name: ____________________________ Date: ______________

Student Worksheet

The table shows surface readings taken on five mornings at Sedgemoor Reservoir, a fictional reservoir. Most fish need dissolved oxygen above 5 mg/L to stay healthy. Use the table for every problem.

Month	Water temperature (°C)	Dissolved oxygen (mg/L)
January	4	11.0
April	12	9.0
July	26	6.5
September	20	7.5
November	10	9.6

What is the range of the dissolved oxygen readings? (Subtract the lowest reading from the highest.)
What is the mean (average) dissolved oxygen across the five months? Round to the nearest tenth.
What is the median dissolved oxygen? (Put the five readings in order and find the middle one.)
Which month had the dissolved oxygen closest to the 5 mg/L level fish need? Does any month fall below 5 mg/L?
Describe the pattern between water temperature and dissolved oxygen in this table.
In which month would fish be most stressed for oxygen, and why?
A shallow pond near the reservoir warms to 30°C in summer. Predict whether its summer oxygen would be higher or lower than Sedgemoor's July reading, and explain your prediction using the pattern.
The mean oxygen for the year was about 8.7 mg/L. Explain why the mean alone does not tell you whether the fish were ever short of oxygen during the year.

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: 4.5 mg/L.
Highest 11.0 minus lowest 6.5 = 4.5 mg/L.
Answer: 8.7 mg/L.
11.0 plus 9.0 plus 6.5 plus 7.5 plus 9.6 = 43.6. 43.6 divided by 5 = 8.72, which rounds to 8.7 mg/L.
Answer: 9.0 mg/L.
In order the readings are 6.5, 7.5, 9.0, 9.6, 11.0. The middle value is 9.0 mg/L.
Answer: July, and no month falls below 5 mg/L.
July's 6.5 mg/L is the closest to the 5 mg/L level. Every month is at or above 5 mg/L, so none falls below it.
Answer: As water temperature goes up, dissolved oxygen goes down. The warmest month, July, has the lowest oxygen, and the coldest month, January, has the highest. The two move in opposite directions.
Answer: July. It is the warmest month at 26°C and has the lowest dissolved oxygen at 6.5 mg/L, so fish would have the least oxygen available then.
Answer: Lower. The pond at 30°C is warmer than the reservoir was in July, and warmer water holds less dissolved oxygen, so the pond's summer oxygen should be lower than Sedgemoor's July reading of 6.5 mg/L.
Answer: The mean smooths the readings into one number, so it hides the lowest value. Fish are stressed during the lowest-oxygen month, not during an average month, so you have to look at the range or the smallest reading, not just the mean, to judge whether they were ever short of oxygen.

Differentiation

Support

Provide the five oxygen readings already listed in order for item 3, and give the sum (43.6) already found for item 2 so students only divide. Let students use a calculator and highlight the highest and lowest readings before starting item 1.

Extension

Ask students to sketch a simple line graph with temperature on one axis and dissolved oxygen on the other, plot the five months, and write one sentence about what the shape of their graph shows about the relationship.

ELL supports

Pre-teach dissolved oxygen, range, mean, and median with a simple picture (bubbles of oxygen in water) and a worked number line for the median. Allow answers to items 5 through 8 as short phrases, and provide the frame "When the water is warmer, the oxygen is ___."