Math problem set Grade 3 Math

Aspen Ridge Dam Gates: A Grade 3 Two-Step Word Problem Set

A grade 3 problem set of two-step word problems about water released through the gates of a fictional dam, with rounding used to check each answer.

Grade: Grade 3
Subject: Math
Material: Math problem set
Time: 40 min
Prep: No prep
Materials: None

Standards

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: Each problem is a two-step word problem solved with the four operations, problem 6 checks the answer by rounding to the nearest hundred, and problem 10 checks an answer with mental math, exactly what this standard requires.

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 solve two-step word problems using multiplication with addition or subtraction.
Students will use rounding to check whether an answer is reasonable.

Vocabulary

Key words: two-step problem, equation, round, gate

Teacher overview

Aspen Ridge Dam (a fictional dam) holds back a lake and lets water through gates into channels below. Each problem in this set takes two steps: students do one operation, then a second, to reach the answer. Problem 6 asks students to round first and check that the exact answer is close, and problem 10 asks them to check another student's answer with mental math, which builds the habit of judging whether a result is reasonable. A common error at this grade is stopping after the first step, such as multiplying but forgetting to add the leak; the two-step wording is designed to catch that.

Aspen Ridge Dam Gates: A Grade 3 Two-Step Word Problem Set — Grade 3 Math

Name: ____________________________ Date: ______________

Problems

Aspen Ridge Dam lets water through gates. All water here is measured in liters.

The dam opens 6 gates. Each gate lets out 40 liters in one minute. A crack also leaks 30 liters in that minute. How many liters flow out in all in one minute?
A test tank holds 800 liters. Workers let out 250 liters, then let out 150 liters more. How many liters are left in the tank?
A worker fills 5 buckets with 20 liters each. Then he pours 40 liters back into the river. How many liters are left in the buckets?
Two channels each carry 60 liters. A third channel carries 90 liters. How many liters do the three channels carry in all?
A fish ladder has 8 steps. Each step holds 10 liters. A ranger adds 20 more liters at the top. How many liters are in the ladder?
One gate lets out 190 liters, then lets out 220 liters. First round each number to the nearest hundred and add to guess the total. Then find the exact total.
A crew works 4 gates. Each gate spills 20 liters. Then the crew cleans up 60 liters of the spill. How many spill liters are left?
Write an equation with a letter for the total t: 3 gates each let out 50 liters, then 25 liters leak. Solve for t.
The lake tank holds 500 liters. Workers add 6 buckets of 30 liters each. How many liters are in the tank now?
A student solved this: 4 buckets of 20 liters, then pour out 30, and got 110 liters. Use mental math to check. Is 110 a reasonable answer?

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: 270 liters. Step 1: 6 gates × 40 liters = 240 liters. Step 2: 240 + 30 leaked = 270 liters.
Answer: 400 liters. Step 1: 800 − 250 = 550 liters. Step 2: 550 − 150 = 400 liters left.
Answer: 60 liters. Step 1: 5 buckets × 20 liters = 100 liters. Step 2: 100 − 40 = 60 liters left.
Answer: 210 liters. Step 1: 2 channels × 60 liters = 120 liters. Step 2: 120 + 90 = 210 liters.
Answer: 100 liters. Step 1: 8 steps × 10 liters = 80 liters. Step 2: 80 + 20 = 100 liters.
Answer: 410 liters. Guess: 190 rounds to 200 and 220 rounds to 200, so 200 + 200 = 400 liters. Exact: 190 + 220 = 410 liters, which is close to the guess of 400.
Answer: 20 liters. Step 1: 4 gates × 20 liters = 80 liters. Step 2: 80 − 60 cleaned = 20 liters left.
Answer: 175 liters. The equation is t = (3 × 50) + 25. Step 1: 3 × 50 = 150. Step 2: 150 + 25 = 175, so t = 175 liters.
Answer: 680 liters. Step 1: 6 buckets × 30 liters = 180 liters. Step 2: 500 + 180 = 680 liters.
Answer: No. Step 1: 4 buckets × 20 liters = 80 liters. Step 2: 80 − 30 = 50 liters. The answer should be about 50 liters, so 110 is not reasonable.

Differentiation

Support

Give students a two-box graphic organizer labeled "Step 1" and "Step 2" so they record each operation before combining. Provide a printed times chart for the multiples of ten used here, and let students solve problems 1 through 4 with a partner. Circle the two numbers each step needs before they compute.

Extension

Ask students to write a two-step gate problem of their own where the first step is multiplication and the second is subtraction, then solve it and check it by rounding. Have them explain why the rounded guess in problem 6 is a little smaller than the exact total.

ELL supports

Pre-teach "gate," "channel," "leak," and "round" with a labeled dam drawing. Provide sentence frames for each step: "First I ___ to get ___. Then I ___ to get ___." Let students state both steps aloud to a partner before writing, and accept an equation with a labeled drawing for problem 8.