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## General

Students learn to add to 100 by tens and ones, which means they split the second addend into tens and ones and add those separately to the first addend.

2.NBT.B.5

## Relevance

Discuss with students that they can use adding by tens and ones to solve addition problems that are too difficulty to solve in your head in one go. An example is if if 38 cars are waiting for the light to turn green and 18 more stop at the light, you can use adding by tens and ones to determine that 56 cars are waiting for the light to turn green.

## Introduction

Ask students to determine whether the given statements about decomposed numbers are true or false. They stand for false, and sit for true.

## Development

Check that students understand adding to 100 using tens and ones by asking the following question:
- How do you add using tens and ones.

## Guided practice

The students first practice calculating the total of an addition problem on the number line. Students are then show then steps taken on a number line but must add the total, finally students must add by tens and ones.

## Closing

Discuss with students that it is important to be able to add to 100 using tens and ones, and being able to split the second addend into two parts because it will make it easier to add larger numbers. Ask students to determine which addition problem matches the number line shown. Students must then complete the addition problems shown on the interactive whiteboard. Drag the numbers to their correct places.

## Teaching tips

Students who have difficulty adding using tens and ones can make use of the number line. Ask them to calculate and draw on the number line the steps to calculate with tens and ones. Emphasize that they first jump with tens and then with ones. Show them that they can also take smaller steps with the ones to reach the next ten, before counting on.

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