Classroom activity Grade 5 Math

Springvale Reservoir Balance Relay: A Grade 5 Decimals Game

A grade 5 relay activity where teams add and subtract decimal water-level changes to track a fictional reservoir's balance over one month station by station.

Grade: Grade 5
Subject: Math
Material: Classroom activity
Time: 40 min
Prep: Low prep
Materials: 5 station cards with decimal change amounts, Printed team score sheet, Timer

Standards

5.NBT.B.7 Common Core Math

Add, subtract, multiply, and divide decimals to hundredths, using concrete models or drawings and strategies based on place value, properties of operations, and/or the relationship between addition and subtraction; relate the strategy to a written method and explain the reasoning used.

How this material aligns: At each relay station teams add or subtract a decimal water-level change to a running total, practicing decimal addition and subtraction to hundredths as this standard requires.

All materials for 5.NBT.B.7 →

Download Word file

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 add and subtract decimals to hundredths to track a running total.
Students will explain how a set of positive and negative changes gives a net change.

Vocabulary

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: decimal, running total, change

Teacher overview

This is a small-group relay for teams of 3 to 4 students. Springvale Reservoir is a fictional reservoir whose water level rises and falls over the course of a month as rain, stream flow, releases, and evaporation change it. Each station gives one decimal change in feet, and teams keep a running total that starts at 25.00 feet. The relay teaches decimal addition and subtraction because each team must add or subtract the station's change correctly before moving on.

Activity Directions

Before class, set up 5 stations around the room. Post one card at each: Station 1 "+2.50 ft (rain)," Station 2 "-1.75 ft (release)," Station 3 "+0.80 ft (stream)," Station 4 "-0.45 ft (evaporation)," Station 5 "Final check."
Put students in teams of 3 to 4. Give each team a score sheet that starts the reservoir at 25.00 feet.
Explain the rule: at each station the team adds or subtracts the posted decimal change to their running total, shows the work on the score sheet, and only then moves to the next station.
Send teams to Station 1. When a team finishes the math, a runner brings the score sheet to you for a quick check before the team moves on.
Teams move through Stations 1 to 4 in order, updating the running total at each one.
At Station 5, teams compare their final level with the total change from start to finish and write both numbers.
End the relay when every team has finished Station 5, or after 20 minutes, whichever comes first.
Gather the class and use the debrief questions on the score sheet to check the final level and the net change together.

Springvale Reservoir Balance Relay: A Grade 5 Decimals Game — Grade 5 Math

Name: ____________________________ Date: ______________

Student Handout

Team score sheet. The reservoir starts at 25.00 feet. Show your work.

Start at 25.00 ft. Rain adds 2.50 ft. What is the new level?
From your answer to item 1, a release lowers the level 1.75 ft. What is the new level?
From your answer to item 2, a stream adds 0.80 ft. What is the new level?
From your answer to item 3, evaporation lowers the level 0.45 ft. What is the new level?
The level began at 25.00 ft and ended at your item 4 answer. How much did it change in all?
Explain in one or two sentences how adding the four changes (+2.50, -1.75, +0.80, -0.45) gives the same net change you found in item 5.

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: 27.50 ft. 25.00 + 2.50 = 27.50 ft.
Answer: 25.75 ft. 27.50 - 1.75 = 25.75 ft.
Answer: 26.55 ft. 25.75 + 0.80 = 26.55 ft.
Answer: 26.10 ft. 26.55 - 0.45 = 26.10 ft.
Answer: 1.10 ft. The level rose from 25.00 ft to 26.10 ft, so 26.10 - 25.00 = 1.10 ft.
Answer: Adding the four changes gives 2.50 - 1.75 + 0.80 - 0.45 = 1.10 ft, the same net change, because the running total is just those four changes applied one at a time.

Differentiation

Support

Give struggling teams a score sheet with the decimal points already lined up in a column for each station so they only fill in the digits. Let them use a place-value chart.

Extension

Add a sixth station with a change of your choice and ask teams to predict the new final level before they compute it, then check their prediction against the actual total.

ELL supports

Label each station card with a small picture (a rain cloud, an open valve, a stream, a sun) beside the words. Provide a sentence frame for item 6: "The four changes add up to ___ feet because ___."