 # Addition to 100 without regrouping

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## General

Students learn to add to 100 without regrouping.

2.NBT.B.5
2.OA.A.1

## Relevance

It is important for students to be able to add to 100 so they are able to determine combined amounts.

## Introduction

Start by practicing the number line to 100 by giving each student a pen/paper and to write a number from 0 to 100. They must then place their number on the number line shown a the front of the class. Next, practice with two addition problems to 50 on the number line.

## Development

Start by discussing the importance of being able to add to 100. Next the learning goal is explained in three forms, visually, in the abstract and in story problems. You can navigate through these by using the menu in the bottom right of the page. Choose which method best suits your classroom needs or go through them all. In the visual- you explain using the images how to add to 100 by counting the images. Practice this with a few exercises. Then in the abstract you discuss different methods by which they can add numbers without counting objects, like using the number line, making tens, adding in tens and units, and doing the calculation in their heads. Practice with a few exercises. Finally the steps of doing a story problem are given. Ask students if they can determine the addition problem from a story problem and solve.

Check that students can add to 100 by asking the following questions:
- Why is it useful to be able to add to 100?
- What do you look at first when adding to 100?

## Guided practice

Students first practice an addition problem with visual support, then without visual support, and then are given a story problem to solve.

## Closing

Give students a money problem and one abstract problem to solve. Ask which method they use to find the total and emphasize that students should use the one they are most comfortable with.

## Teaching tips

Students who have difficulty adding to 100 can be helped by the use of manipulatives or by making use of the number line.

## Instruction materials

Paper for introduction exercise
Optional: blocks or manipulatives 