Math problem set Grade 3 Math

Skellingate Dam's Wheel Week: A Grade 3 Two-Step Problem Set

Ten grade 3 problems tracking one week at a fictional dam, mixing two-step multiplication and subtraction with clock-time intervals from the crew's log.

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: Problems 7 and 10 are two-step problems in which students must combine a multiplication or an addition with a second operation before answering.

All materials for 3.OA.D.8 →

3.MD.A.1 Common Core Math

Tell and write time to the nearest minute and measure time intervals in minutes. Solve word problems involving addition and subtraction of time intervals in minutes, e.g., by representing the problem on a number line diagram.

How this material aligns: Problem 6 asks students to find the number of minutes between two clock times in the gate log, and problem 5 applies the same elapsed-time reasoning across whole hours.

All materials for 3.MD.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 2026-07-23.

Objectives

Students will multiply to find weekday and weekend running hours and add the two totals.
Students will solve two-step problems about a dam crew's schedule using the four operations.
Students will find a finish time and a minute interval from clock times in a log.

Vocabulary

Dam: A strong wall built across a river to hold back water. Dams store water for people and farms, help prevent floods, and can make electricity.
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: gate, water wheel, crew, log

Teacher overview

A dam holds back a lake, and the water that leaves through its gates can be made to spin a wheel that produces electricity. This set follows one week at the fictional Skellingate Dam, where a small crew logs running hours, gate openings, and walking rounds. The misconception the set is built to correct is the habit of multiplying a daily amount by seven for a whole week even when the schedule is not the same every day, since here the wheel runs eight hours on weekdays and only five hours on weekend days.

Skellingate Dam's Wheel Week: A Grade 3 Two-Step Problem Set — Grade 3 Math

Name: ____________________________ Date: ______________

Problems

The fictional town of Dunwarren draws its water from a lake behind Skellingate Dam. Water leaving the dam spins a wheel that makes electricity for the town's water plant. A crew keeps a log of the week.

The wheel runs 8 hours on each weekday. A week has 5 weekdays. How many hours does the wheel run on the weekdays?
The wheel runs 5 hours on each weekend day. A week has 2 weekend days. How many hours does the wheel run on the weekend?
The wheel ran 40 hours on the weekdays. It ran 10 hours on the weekend. How many hours did it run in the whole week?
Last week the wheel ran 46 hours. This week it ran 50 hours. How many more hours did it run this week?
On Monday the wheel starts at 7:15 a.m. It runs for 8 hours with no stops. What time does it stop?
The crew opens a gate at 6:40 a.m. They close it at 7:15 a.m. How many minutes was the gate open?
The crew walks the top of the dam 3 times a day. Each walk takes 12 minutes. On Wednesday they add one more walk. How many minutes do they walk on Wednesday?
The crew wrote down 128 gate checks in June. They wrote down 145 gate checks in July. How many gate checks is that in all?
The crew wrote down 145 gate checks in July and 128 gate checks in June. How many more checks were there in July?
The wheel was set to run 50 hours this week. It was shut off for 6 hours on Thursday and for 4 hours on Friday. How many hours did it really run?

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: 40 hours. Five weekdays with 8 hours on each day gives 5 times 8, which is 40 hours.
Answer: 10 hours. Two weekend days with 5 hours on each day gives 2 times 5, which is 10 hours.
Answer: 50 hours. 40 plus 10 is 50 hours. Students who instead multiply 8 by 7 and answer 56 hours have used the weekday amount for the weekend days as well.
Answer: 4 hours. 50 minus 46 is 4 hours.
Answer: 3:15 p.m. From 7:15 a.m., five hours reaches 12:15 p.m., and three more hours reaches 3:15 p.m., for 8 hours in all.
Answer: 35 minutes. From 6:40 to 7:00 is 20 minutes. From 7:00 to 7:15 is 15 more. 20 plus 15 is 35 minutes.
Answer: 48 minutes. Three walks plus one more walk is 4 walks. Then 4 times 12 is 48 minutes.
Answer: 273 gate checks. 128 plus 145 is 273. Add 100 and 100 to get 200, then 28 and 45 to get 73, then 200 plus 73.
Answer: 17 gate checks. 145 minus 128 is 17. Counting up from 128 to 145 gives the same 17.
Answer: 40 hours. The two shutdowns add to 6 plus 4, which is 10 hours. Then 50 minus 10 is 40 hours.

Differentiation

Support

Give these students counters or a printed 100 chart, and let them build problems 1 and 2 as equal groups before writing the multiplication sentence. Assign problems 1, 2, 3, 4, and 6, and supply a paper clock face for problem 6. Read each problem aloud twice, pausing after the numbers.

Extension

Ask students to plan a different week for the fictional Skellingate crew in which the wheel still runs 50 hours in total but no day runs longer than 9 hours. They should write the hours for all seven days, show that the sum is 50 hours, and explain one reason a crew might want the shorter days.

ELL supports

Pre-teach "dam," "gate," and "crew" with a labeled sketch of a dam holding back a lake, with an arrow showing water leaving through a gate. Provide the frames "___ groups of ___ hours is ___ hours" and "From ___ to ___ is ___ minutes." Let students point to the numbers in the problem they used before they write.