Math problem set Grade 3 Math

Fernbrook Water Plant's Storage Tanks: A Grade 3 Liter Problem Set

A grade 3 math problem set where students add and subtract liter volumes for two storage tanks at a fictional water treatment plant to track fill levels.

Grade: Grade 3
Subject: Math
Material: Math problem set
Time: 35 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, 2, 4, 5, 6, and 7 add and subtract liter volumes between Fernbrook's two storage tanks and a delivery truck, working with the same measurement unit throughout as this standard requires.

All materials for 3.MD.A.2 →

3.NBT.A.2 Common Core Math

Fluently add and subtract within 1000 using strategies and algorithms based on place value, properties of operations, and/or the relationship between addition and subtraction.

How this material aligns: Every addition and subtraction in the set stays within 1000 and uses three-digit liter totals, the fluent place-value computation within 1000 this standard targets.

All materials for 3.NBT.A.2 →

3.OA.A.1 Common Core Math

Interpret products of whole numbers, e.g., interpret 5 x 7 as the total number of objects in 5 groups of 7 objects each. For example, describe a context in which a total number of objects can be expressed as 5 x 7.

How this material aligns: Problem 3 interprets 3 times 90 as the total liters in three equal batches of 90 liters each, the equal-groups meaning of multiplication this standard defines.

All materials for 3.OA.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 2026-07-16.

Objectives

Students will add and subtract liter volumes within 1000 to track two storage tanks' fill levels.
Students will interpret a multiplication expression as equal groups of liters.
Students will solve a two-step problem that combines two tanks' amounts for a delivery truck.

Vocabulary

Key words: capacity, batch, combined, remaining

Teacher overview

The fictional Fernbrook Water Treatment Plant stores clean water in two tanks before it goes out to homes: Tank 1 holds up to 480 liters when full, and Tank 2 holds up to 350 liters when full. Real treatment plants store far more water than this, often millions of liters, and the tank sizes in this problem set are kept small so that every calculation stays within 1000. This problem set follows the two tanks through one morning, adding and subtracting their liter levels as water is pumped in and used. A common misconception is confusing "how much is currently in the tank" with "how much more is needed to fill it"; problem 2 is built to catch students who add the tank's current amount to its full capacity instead of subtracting one from the other.

Fernbrook Water Plant's Storage Tanks: A Grade 3 Liter Problem Set — Grade 3 Math

Name: ____________________________ Date: ______________

Problems

Tank 1 holds up to 480 liters when full. Tank 2 holds up to 350 liters when full. What is the full capacity of both tanks together?
Tank 1 has 275 liters in it this morning. How many more liters would fill Tank 1 all the way?
Tank 2 starts the morning empty. The plant pumps in 3 batches. Each batch is 90 liters. How many liters are in Tank 2 after all 3 batches?
Use your answer from problem 3. How many more liters can Tank 2 still hold before it is full?
Tank 1 had 275 liters. The plant uses 65 liters to test the water. How many liters are left in Tank 1?
A truck loads the water left in Tank 1 (your answer from problem 5). It also loads all of Tank 2's water (your answer from problem 3). How many liters does the truck load in all?
The truck's tank holds up to 500 liters. Use your answer from problem 6. How many more liters of room does the truck have before it is full?
The plant checks Tank 1's level for 3 days. Day 1: 210 liters. Day 2: 180 liters. Day 3: 240 liters. What is the total of these three readings added together?

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: 830 liters.
480 liters (Tank 1) + 350 liters (Tank 2) = 830 liters combined.
Answer: 205 liters.
Tank 1's full capacity is 480 liters, and it currently has 275 liters: 480 − 275 = 205 liters more are needed.
Answer: 270 liters.
Three batches of 90 liters each is three equal groups of 90: 3 × 90 = 270 liters.
Answer: 80 liters.
Tank 2 holds up to 350 liters and currently has 270 liters (from problem 3): 350 − 270 = 80 liters of room remain.
Answer: 210 liters.
Tank 1 had 275 liters, and the plant used 65 liters for testing: 275 − 65 = 210 liters remain.
Answer: 480 liters.
Tank 1's remaining 210 liters (from problem 5) plus Tank 2's 270 liters (from problem 3): 210 + 270 = 480 liters loaded onto the truck.
Answer: 20 liters.
The truck can hold up to 500 liters and is carrying 480 liters (from problem 6): 500 − 480 = 20 liters of room remain.
Answer: 630 liters.
Adding the three daily readings: 210 + 180 + 240 = 630 liters total across the three days.

Differentiation

Support (below grade level)

Provide a place-value chart with hundreds, tens, and ones columns for every addition and subtraction problem, and allow students to use base-ten blocks or a hundreds chart for regrouping. Give students the answer to problem 3 (270 liters) already computed if the multiplication step is too difficult, so they can still complete problems 4, 6, and 7.

Extension (above grade level)

Ask students to find how many liters both tanks combined would need to go from their current levels (Tank 1 at 210 liters after problem 5, Tank 2 at 270 liters) up to both tanks being completely full at the same time, showing every step of their reasoning.

ELL supports

Pre-teach "capacity," "batch," and "remaining" using a simple picture of two labeled tanks with a fill line drawn partway up each one. Provide a sentence frame for problem 2 and problem 4: "Tank ___ needs ___ more liters to be full."

Extensions

Have students track their own classroom's water bottle refill station for one school day, recording how many liters or cups are used at three different times, and write one addition problem and one subtraction problem using their own real numbers, modeled on this problem set's structure.