Addition through 100 without regrouping

General

Students can add beyond 100 without regrouping.

Common core standard(s)

2.NBT.B.5
1.NBT.C.4

Relevance

Discuss with students that it is important to be able to add beyond 100, so you know how much you have, and so you learn how to be able to add to 1,000.

Introduction

First practice by reviewing the number line to 100 with your students. Ask them to place random numbers on the number line to 100. Then they must take number cards and find their way to their place as a living number line. And finally, ask a student to count past 100. Check their counting by erasing the squares on the interactive whiteboard.

Development

Discuss with students why it is important to be able to add beyond one hundred. Show them an example addition problem in which you add beyond 100. This learning goal will be discussed in three ways, visually, in the abstract and in story problems. You can use the menu in the bottom right to select the method that best suits your classroom needs. It starts with visual explanation. Using the blocks, discuss how you can add through 100. Ask students to practice with visually supported addition problems with blocks and ten-frames. Then the abstract. Tell students that they can solve these abstract addition problems by adding to one hundred and then to do the rest of the calculation. This can be done on a number line or without the number line. Students can also split both addends into tens and ones and add those separately to find the total. Ask students to practice with a method they like best on a few addition problems. Finally the steps of solving a story problem are given and students can solve a story problem together as a class. Every method has explanation first, then practice, and finally has a few exercises students can do to check their mastery.

Check that students are able to add beyond 100 without regrouping by asking the following questions:
- Why is it useful to be able to add beyond 100?
- What is useful to do when you calculate beyond 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

Discuss the learning goal again with the students. Then check that students have understood by asking them to do another addition problem. There are three given, one visually supported, one abstract, and one story problem. Ask students to explain the steps they took to solve the different problems.