# Surf for More Math

## CHAPTER 6: ADDITION AND SUBTRACTION

**Lesson 1: Estimating Sums**

Use these interactive activities to encourage students to have fun on the Web while learning about estimating sums. Students can try these activities on their own or in pairs.

**Goal**

Estimate sums of 2-digit numbers to solve problems.

**Builds Upon **

Student Book pages 136–137

**Instructions for Use**

Estimation Contraption asks students to estimate sums. Note that Level 1 is most appropriate for students.

Click “Instructions” to read about estimating, then click “Play Game.” Before the time runs out, estimate the total. Type your estimate in the box, then click “OK.” When Level 1 is complete, click here to play again.

Estimating a Sum allows students to practise estimating sums of 2-digit numbers using tens.

Scroll down the page to the section marked “Practice,” then click “Start.” Read the numbers in the white boxes, and estimate their sum. Select the sum from the buttons. Beneath these buttons, a message will appear to tell you if you answered correctly or not. Then read the next problem in the white boxes beneath the “Start” button.