 Addition to 20 on the number line

# Addition to 20 on the number line 8,000 schools use Gynzy 92,000 teachers use Gynzy 1,600,000 students use Gynzy

## General

Students learn to add to 20 on the number line without carrying numbers.

## Relevance

It is important to add so you know how many you have when amounts join.

## Introduction

The interactive whiteboard shows the the number line from one to twenty, with four numbers hidden behind balls. The students must determine which numbers are hidden, and you can drag the balls away to show the answer.

## Development

First discuss with students how they can count the tennis balls on the interactive whiteboard. Next, use three steps to explain how to add numbers on the number line. First you must look at the first addend of the addition problem to determine where you start on the number line. Then, you must look at the second addend. That represents how far you move on the number line. After moving that number of steps, you look to see where you end up on the number line, as that is your total. To check that students are able to add using the number line, have the class solve a few addition problems. Emphasize that the students may choose how far to move in one go on the number line, they can go one by one, but also in larger jumps.

To check that students can add to 10 on the number line without carrying numbers, you can ask the following questions:
- Which addend tells you where to start on the number line?
- Which addend tells you how far you move on the number line?
- How do you know what the total is?

## Guided practice

Students practice adding on the number line, starting with smaller and moving to larger numbers to add together.

## Closing

Repeat why it is important that students are able to add to twenty. The interactive whiteboard shows an addition problem with a number line. Students calculate the answer by making jumps along with the board. You can ask students to determine how to move on the number line in groups and then discuss as a class which options are possible.

## Teaching tips

If students have difficulty with this goal, it is important to make sure they are comfortable with counting to20. You can have students write all the numbers to 20 below the number line and have them add by taking steps of +1 rather than larger steps.

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