Addition to 1,000 crossing tens

General

In this lesson students learn to add numbers up to 1,000 crossing multiples of ten.

Standards

CCSS.Math.Content.2.NBT.B.7

Learning objective

Students will be able to add numbers to 1,000 crossing multiples of ten.

Introduction

Together with students, build an addition problem to 1,000 using MAB blocks and discuss the problem.

Development

Tell students that you can add by counting. You first start by counting how many you already have, that is the first addend in the problem. Then you count how many you are adding, that is the second addend in the problem. When you count these together, you find the total. Show this on the interactive whiteboard using blocks and showing the different problems. Check that students are able to add by counting on with the block and money. Next explain that you can add in different ways. You can make use of a number line, or count in steps to the next hundred, and cross the hundred. You can also choose to first add all the, ones, tens, and hundreds and add them together to find the total. Explain that you can split the number a variety of ways to then add it together in parts. Show students a few problems and ask them to find the total. Ask them to explain their strategy. Then show students how to solve a story problem. Walk them through the steps of solving a story problem. First determining what kind of story problem it is, then determining which numbers are important for the story problem. Then they must say or write the problem, and finally solve the problem. Solve a story problem together as a class and then ask students to solve a story problem individually or in pairs.

Check that students are able to add numbers to 1,000 crossing tens by asking the following questions:
- Why is it useful to be able to add to 1,000?
- What are different ways to add two numbers together?

Guided Practice

Students are given various addition problems that include problems with visual support, abstract problems, and story problems.

Closing

Discuss with students that it is important to be able to add to 1,000 crossing multiples of ten so that you can find the total. Show the blocks on the interactive whiteboard and ask students to determine which problem matches the blocks. Then determine the total. Give students a few more problems to solve, including a story problem and ask students to explain their strategy for the problems.

Teaching tips

Students who have difficulty adding and crossing multiples of ten can be supported by making use of manipulatives like MAB Blocks or making use of the number line. Show students that they can make jumps in addition in different ways, and show how they are represented on the number line. Start with simple addition problems that cross tens like 153 + 9. Then as students become more comfortable, introduce problems like 118 + 25 and 367 + 127.