## CHAPTER 3: ADDITION AND SUBTRACTION STRATEGIES

**Lesson 11: Subtracting 2-Digit Numbers**

**Goal**

Subtract 2-digit numbers using your own strategies.

**Instructions for Use**

Subtraction Machine provides 2-digit subtraction problems for you to solve and check your answers.

Click the lever above “Level 3” to make a subtraction problem appear in the centre of the screen. Type your answer in the white box, then click on the red button to check your answer. Click on the “Level 3” lever to see the next subtraction problem.

Ghost Blasters (Subtraction) has your solve 2-digit subtraction problems by choosing the correct answer. Note that two players are required for this game.

After reading the instructions, click “Next.” Enter both players’ names in the boxes, then click “Begin.” The player who is supposed to answer each question is shown in red below the subtraction problem. Read the subtraction problem at the bottom of the screen, then click on the ghost that contains the correct answer.