Addition to 1,000 crossing hundreds

General

Students learn to add numbers up to 1,000 crossing hundreds.

Standards

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

Learning objective

Students will be able to add up to 1,000, crossing multiples of 100.

Introduction

Show three numbers on the interactive whiteboard. Have students work in pairs to determine the largest possible number that they can create with the three given digits. Ask them to place the created number into the HTO chart. Then they have to create the smallest possible number that they can create with the given digits. Ask them to place that into the HTO chart as well. Next, as a class use the MAB blocks to create an addition problem up to 1,000 and discuss the addition problem.

Development

Explain to students that you can add by counting on. You start by counting how many you already have. That is your first addend. Then you count how many more you are adding, that is your second addend. When you count the two together, you find the total. Show this on the interactive whiteboard using the blocks and demonstrate a few problems. Check that students are able to do this by asking them to add the given blocks and money shown on the interactive whiteboard. Next explain to students that there are different ways to add two numbers together. One of those ways is to use a number line. You can also add in steps, first adding the hundreds, then the tens, and finally the ones. You can also add the different place value numbers separately, adding only the hundreds, only the tens, and only the ones and adding all of those totals together. Ask students to solve a few addition problems. Have them explain their strategy. Finally remind students how to solve a story problem. They first must determine what kind of math problem is in the story, then they must determine which numbers are important to the math problem. Next they must say or write the math problem, and finally they 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 hundreds by asking the following questions:
- Why is it useful to be able to add numbers to 1,000?
- What are some different ways to add numbers together?

Guided Practice

Students are given a set of practice exercises which present addition problems to 1,000 in a visual form, with abstract questions, and some story problems.

Closing

Discuss with students that it is important to be able to add numbers to 1,000 crossing hundreds, so that you can find the totals of quantities. Show the blocks on the interactive whiteboard and ask students which problem matches the image and then ask students to solve the problem. Next ask students to solve an abstract problem, and close with a story problem. Make sure to ask students to explain their strategy as they solve the addition problems.

Teaching tips

Students who have difficulty with this learning goal can be supported by making use of MAB blocks or other manipulatives, or by using a number line to help visualize the addition process. Remind students that the steps of addition can be taken in different ways, and show this with jumps of 1, 2, 5, 10 (etc) on the number line. Start with simple addition problems that easily cross hundreds like 151 + 60 and then increase difficulty with problems like 173 + 142.