# ﻿Representing Subtraction

Warmup

Study the arrow diagrams below and choose which answer it represents.

Activity #1

Represent Subtraction Problems on a Number Line.

Here below is an unfinished number line diagram that represents a sum of 8.

(1.) How long should the other arrow be?

• Draw it on the applet below.

For an equation that goes with the diagram above, Mai writes  3 + ? = 8. Tyler writes  8 – 3 = ?.

(2.) Do you agree with either of them?

(3.) What is the unknown number? How do you know?

Here is another unfinished diagram that represent sums:

(4.) What equation would Mai write if she used the same reasoning as before?

(5.) What equation would Tyler write if he used the same reasoning as before?

(6.) How long should the other arrow be?

(7.) What number would complete each equation? Explain your reasoning.

Here is another unfinished diagram that represents a sum.

(8.) What equation would Mai write if she used the same reasoning as before?

(9.) What equation would Tyler write if he used the same reasoning as before?

(10.) How long should the other arrow be?

(11.) What number would complete each equation? Explain your reasoning.

Activity #2

Complete a Table.

• Complete the tables below. If you get stuck, consider using the applet in Activity #3 underChanging Elevationin UNIT 5.

Activity #3

Match a Diagram to an Equation.

• Answer as many questions as time allows you in this exercise.

Challenge #1

Complete the table below.

Challenge #2

Complete the table below.

Challenge #3

Write the subtraction equation below as an addition equation.

Quiz Time