  # Surf for More Math

## Lesson 2 - Estimating Sums and Differences

To encourage students to have fun on the Web while learning about Estimating Sums and Differences, here are some games and interactive activities they can do on their own or in pairs.

### Goal

Estimate sums and differences to solve problems.

### Builds Upon

Student Book pages 110-111

### Instructions for Use

Estimation Contraption helps students estimate sums.

To use Estimation Contraption, estimate the sum of the column of numbers, and input the answer in the field below the column. Click 'OK' to check if the answer is correct. Try the next question.

Estimating Sums by Rounding allows students to estimate the sum of two numbers using rounding.

To use Estimating Sums by Rounding, click the 'Start Addition' button. Estimate the sum between the two numbers and press the numeric button closest to your estimation.

Estimating Differences by Rounding allows students to estimate the difference of two numbers using rounding.

To use Estimating Differences by Rounding, click the 'Start Subtraction' button. Estimate the difference between the two numbers and press the numeric button closest to your estimation.   