Math problem set Grade 3 Math

Thistle Hollow Rain Barrel: A Grade 3 Water-Saving Math Set

A grade 3 problem set where students add, subtract, and multiply liters to track a fictional family's rain barrel and drippy tap in the town of Thistle Hollow.

Grade: Grade 3
Subject: Math
Material: Math problem set
Time: 30 min
Prep: No prep
Materials: None

Standards

3.MD.A.2 Common Core Math

Measure and estimate liquid volumes and masses of objects using standard units of grams (g), kilograms (kg), and liters (l). Add, subtract, multiply, or divide to solve one-step word problems involving masses or volumes that are given in the same units, e.g., by using drawings (such as a beaker with a measurement scale) to represent the problem.

How this material aligns: Problems 1 through 5 add, subtract, and multiply liters of water in the rain barrel, the one-step liquid-volume word problems in standard units this standard requires.

All materials for 3.MD.A.2 →

3.OA.D.8 Common Core Math

Solve two-step word problems using the four operations. Represent these problems using equations with a letter standing for the unknown quantity. Assess the reasonableness of answers using mental computation and estimation strategies including rounding.

How this material aligns: Problem 6 combines multiplication and subtraction into a single two-step barrel question, and problem 7 asks students to judge a total against an estimate before computing it, the two steps and the reasonableness check this standard names.

All materials for 3.OA.D.8 →

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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 add, subtract, and multiply liters to solve rain barrel problems.
Students will solve a two-step water problem with more than one operation.
Students will check a total by first making an estimate.

Vocabulary

Rain barrel: A rain barrel is a container that catches rainwater from a roof downspout so it can be used later to water plants. It saves drinking water and keeps some runoff out of the storm drains.

Also: liter, estimate

Teacher overview

The Okafor family lives in the fictional town of Thistle Hollow. They catch rain in a barrel and use it to water the garden, which saves tap water. The barrel can hold up to 60 liters. This set has students track the water going into and out of the barrel using grade 3 liquid-volume math. A common mistake to watch for is mixing up how much water is in the barrel with how much empty space is left; problems 2 and 3 are built to make students tell those two amounts apart.

Thistle Hollow Rain Barrel: A Grade 3 Water-Saving Math Set — Grade 3 Math

Name: ____________________________ Date: ______________

Problems

The Okafor family's rain barrel can hold up to 60 liters of water. Use this in every problem.

Monday the barrel gets 15 liters of rain. Tuesday it gets 20 liters. How many liters is that in all?
The barrel already had 10 liters in it. Add the 35 liters from problem 1. How many liters are in the barrel now?
The barrel can hold 60 liters at most. Right now it has 45 liters. How many more liters can still fit?
The family uses 8 liters to water the garden. Start from 45 liters. How many liters are left?
A drippy tap wastes 5 liters each day. How many liters does it waste in 4 days?
The barrel has 37 liters. The family fills two watering cans from it. Each can holds 6 liters. They pour both cans onto the garden. How many liters are left in the barrel?
Three storms add 15 liters, 20 liters, and 5 liters to the barrel. First estimate: is the total closer to 30 or 40 liters? Then find the exact total.

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: 35 liters. 15 + 20 = 35 liters of rain.
Answer: 45 liters. The barrel had 10 liters, plus 35 more, so 10 + 35 = 45 liters.
Answer: 15 liters. The barrel holds 60 and has 45, so 60 − 45 = 15 liters of empty space are left, and 15 more liters can still fit.
Answer: 37 liters. The garden used 8 liters, so 45 − 8 = 37 liters are left.
Answer: 20 liters. A 5-liter drip each day for 4 days is 5 × 4 = 20 liters wasted.
Answer: 25 liters. Two cans of 6 liters is 6 × 2 = 12 liters poured out; 37 − 12 = 25 liters left.
Answer: 40 liters. Estimate: the total is closer to 40. Exact: 15 + 20 + 5 = 40 liters.

Differentiation

Support

Give these students a picture of the barrel with liter lines marked so they can shade the water level for problems 2, 3, and 4. Let them use base-ten blocks or a number line for each add and subtract step.

Extension

Ask these students to plan a week of storms and garden watering so the barrel ends the week with exactly 30 liters, and to show the math that proves it. Have them write one two-step barrel problem for a partner.

ELL supports

Pre-teach "rain barrel," "liter," and "estimate" with a real jug and a picture of a barrel catching rain. Provide the sentence frame "The barrel has ___ liters because ___." Allow number sentences alone, without written words, where the math is correct.

Extensions

Have students find out if their own home or school could catch rain in a barrel and estimate how many liter jugs it would take to hold one storm's water. Connect the set to why towns in dry places save every liter of rain they can.