Section C: Practice Problems Diagrams to Compare

Section Summary

Details

In this section of Unit 1, we learned how to represent and solve Compare problems. First, we used bar graphs to find the difference between two categories.

Horizontal bar graph. Third Grade Family Pets. Horizontal axis from 0 to 18 by ones. Vertical axis labeled rabbit, cat. Length of bar: Rabbit, 8. Cat, 17.

How many more students have cats than have rabbits? Show two ways to find the difference.

We learned about a new representation called a diagram. It helps us make sense of story problems. We can use diagrams to show which part of a comparison we need to find.

Diagram. Two rectangles of equal length. Top rectangle, Noah's pages, partitioned into 2 parts. First part, shaded, total length, 20. Second part has dashed outline, total length, question mark. Bottom rectangle, Jada's pages. Total length, 47.

Jada read 47 pages of the book. Noah read 20 pages of the book. How many fewer pages did Noah read?

In this problem, we are finding the difference. We know how many pages Noah and Jada read, so the ? represents the difference.

Problem 1 (Lesson 13)

The graph shows the number of friends these students had at their birthday parties.

Horizontal bar graph. Party Time. Horizontal axis from 0 to 18 by ones. Vertical axis labeled Noah, Elena, Tyler, Jada. Length of bar: Noah, 14, Elena, 9, Tyler, 11, Jada, 15.

  1. How many fewer friends were at Elena’s party than at Jada’s party?

  2. Write an equation to show how you found the difference.

Problem 2 (Lesson 14)

The bar graph shows the number of connecting cubes of different colors in a bag.

Horizontal bar graph. Connecting Cube Colors. Horizontal axis from 0 to 18 by ones. Vertical axis labeled blue, green, yellow, brown. Length of bar: Blue, 17. Green, 9. Yellow, 6. Brown, 15.

  1. Use the bar graph to complete the tape diagram.

    Diagram. Two rectangles of equal length. Rectangle on top labeled green, partitioned into 2 parts. First part, shaded, total length, blank. Second part has dashed outline, total length, question mark. Rectangle on the bottom labeled brown, shaded, total length, blank.

  2. How many fewer green connecting cubes than brown connecting cubes are in the bag? Show or explain your reasoning.

Problem 3 (Lesson 15)

There are 25 crickets chirping in the front yard.

There are 16 fewer crickets chirping in the front yard than in the back yard.

  1. Label the rectangles to match the story. Explain your reasoning.

    Diagram. Two rectangles of equal length. Rectangle on top blank label, partitioned into 2 parts. First part, shaded, total length, 25. Second part has dashed outline, total length, 16. Rectangle on the bottom blank labeled. Total length, question mark.

  2. Write an equation to represent the story problem.

Problem 4 (Lesson 16)

There are 35 cherries in the bowl. There are 17 more cherries in the bowl than on the plate. How many cherries are on the plate? Show your thinking using drawings, numbers, or words.

Problem 5 (Lesson 16)

There were 26 students in the cafeteria. There were 18 more students on the playground than in the cafeteria. How many students were on the playground? Show your thinking using drawings, numbers, or words.

Problem 6 (Exploration)

Write a story to match the diagram. Explain why the story matches the diagram.

Diagram. Two rectangles of equal length. Rectangle on top partitioned into 2 parts. First part, shaded, length, 26. Second part, dashed outline, length, question mark. Rectangle on the bottom, shaded, total length, 47.

Problem 7 (Exploration)

Write a Compare story problem.

Solve your problem. Include an equation and a tape diagram.