Videos to help Grade 3 students learn how to solve word problems involving time intervals within 1 hour by adding and subtracting on the number line.

Common Core Standards: 3.NBT.2, 3.MD.1

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Lesson Plans and Worksheets for Grade 3

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Common Core For Grade 3

New York State Common Core Math Module 2, Grade 3, Lesson 5

Application Problem

Carlos gets to class at 9:08 a.m. He has to write down homework assignments and complete morning work
before math begins at 9:30 a.m.

How many minutes does Carlos have to complete his tasks before math begins?

Concept Development

Use your number line template to label the points when Carlos arrives and when math starts.

Writing down homework assignments is the first thing Carlos does when he gets to class. It takes 4 minutes. Plot the point that shows when Carlos finishes this first task.

At what time did you plot the point? 9:12 a.m.

What does the interval between 9:12 and 9:30 represent?

The number of minutes it takes Carlos to finish his morning work.

How can we find the number of minutes it takes Carlos to complete morning work?

Count on the number line. Count forward from 9:12 to 9:30.

What addition sentence represents this problem?

12 minutes + ____ = 30 minutes.

Find the number of minutes it takes Carlos to complete morning work.

How many minutes did it take Carlos to finish morning work? 18 minutes.

How could we have modeled that problem by counting backward?

We could have started at 9:30 and counted back until we got to 9:12.

What subtraction sentence represents this problem?

30 minutes – 12 minutes = 18 minutes.

1. Abby spent 22 minutes doing her science project yesterday and 34 minutes doing it today. How many minutes does Abby spend working on her science project altogether? Model the problem on the number line and write an equation to solve.

2. Susanna spends a total of 47 minutes working on her project. How many more minutes than Susanna does Abby spend working? Draw a number line to model the problem and write an equation to solve.

3. Peter practices violin for a total of 55 minutes over the weekend. He practices 25 minutes on Saturday. How many minutes does he practice on Sunday?

4. a. Marcus gardens. He pulls weeds for 18 minutes, waters for 13 minutes, and plants for 16 minutes. How many total minutes does he spend gardening?

4. b. Marcus wants to watch a movie that starts at 2:55 p.m. It takes 10 minutes to drive to the theater. If Marcus starts the yard work at 2:00 p.m., can he make it on time for the movie? Explain your reasoning.

5. Arelli takes a short nap after school. As she falls asleep the clock reads 3:03 p.m. She wakes up at the time shown below. How long is Arelli's nap?

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