# Surf for More Math

## CHAPTER 3: ADDING AND SUBTRACTING DECIMALS

**Lesson 3: Estimating Decimal Sums and Differences **

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

**Goal**

Estimate sums and differences with decimals.

**Builds Upon**

Student Book pages 88–91

**Instructions for Use**

**Laser Beam** allows students to estimate sums and differences by rounding decimals.

Blast meteors as you answer addition and subtraction questions. Select the “Intermediate” level. Round the decimals and then estimate the sum or difference.

**Math at the Mall ** allows students to add and subtract decimals to purchase items at the mall.

Use the arrow keys to move your character around the mall. To get the various places in mall, please move your character to the very end of the pathway. At every location you will have to use your adding and subtracting skills to complete several tasks, such as depositing money at the bank, or purchasing toys at the toy store.