# Surf for More Math

## CHAPTER 3: ADDITION AND SUBTRACTION STRATEGIES

**Lesson 5: Using a 100 Chart to Add and Subtract**

Use these interactive activities to encourage students to have fun on the Web while learning about using a 100 chart to add and subtract. Students can try these activities on their own or in pairs.

**Goal**

Add tens to 2-digit numbers or subtract tens from 2-digit numbers.

**Builds Upon**

Student Book pages 66–67

**Instructions for Use**

Target Number +11 has students add 11 to a given number and indicate the result on a 100 chart.

Click the red button to start. Add 11 to the target number at the bottom right. Click the correct number on the chart. If the number you clicked is correct, the time taken appears at the top right. Click on the red button to continue to the next number.

Give the Dog a Bone has students find 10 bones on a blank 100 chart by using addition to determine the position of the target number.

Click the “begin” button at the bottom right to start. Find the number shown in the white box at the right on the 100 chart by adding by 10s downwards and 1s toward the right, starting from 1 at the top left square. You have 60 seconds to find 10 bones.

Splat Square provides a 100 chart for students to use to answer any addition or subtraction problem. You can use this chart for activities on an interactive whiteboard. 20 Things to Do with a Hundred Chart has many helpful suggestions on activities to do with a 100 chart.

Click “Begin,” then choose a colour to “splat” from the right side of the screen. Click on a square on the 100 chart to “splat” the colour. You may want to change colours to help you solve addition and subtraction problems. When you wish, click “Clear” to clear the screen and start over.