# Surf for More Math

## Chapter 5: Number to 20

**Lesson 2: Counting On and Back from 10 to 20**

Use these interactive activities to encourage students to have fun on the Web while learning about number to 20. Students can try these activities on their own or in pairs.

**Goal**

Create sets of between 10 and 20 objects by adding or subtracting one or two.

[C, CN, R, V]

**Instructions for Use**

**Dot to Dot** allows students to count backward from 20 to 1, to create a picture.

Click on “20” and count backward to 1 to create a picture.

**Addition Number Line** allows student to use this virtual number line to help them solve addition sentences.

Use the number line to help you solve the addition sentence shown. Type your answer in the empty text box. Click “Check” to check your answer. Click the arrow to try another addition sentence.

Subtraction Number Line allows student to use this virtual number line to help them solve subtraction sentences.

Use the number line to help you solve the subtraction sentence shown. Type your answer in the empty text box. Click “Check” to check your answer. Click the arrow to try another subtraction sentence.