Addition to 50 with second addends <10

General

Students learn to add to 50 with second addends that are less than 10.

Common core standard(s)

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

Relevance

It is important to be able to add to 50, so you can determine amounts together.

Introduction

Ask students to calculate an addition problem on the number line. Explain step by step how you reach the answer. On the next slide, students can choose where the frog goes. Drag the frog to the right and count forwards, or drag the frog to the left and count backwards. Have students count aloud with the movement the frog makes.

Development

Discuss with students the importance of being able to add to 50. This goal is taught in three ways, visually, in the abstract, and as story problems. You can select one using the menu in the bottom right of the page. You can decide which method is best suited to your class. In the visual method, first count the objects with your students. Then show how to add the second addend to the first. Check that students can solve visually supported addition problems. In the abstract, addition problems can be solved a few different ways. Show how they can use a number line to solve the problem or can solve the problem directly. With the story problems, first describe the steps to solve a story problem, and then practice solving a story problem.

Check that students understand adding to 50 with second addends <10 by asking the following questions:
- Why is it useful to be able to add to 50?
- How do you calculate an addition problem to 50?

Guided practice

Students first practice visually supported addition problems. They then are given an abstract addition problem, and finally must solve a word problem.

Closing

Check that students have understood by asking how they solve an addition problem to 50. Emphasize that each student might use a different method to solve, and that they are all good methods. Finally, students must solve five different "balloon" problems. The problems have a timer that can be used to increase excitement and intensity. You can adjust the length of the timer to make it easier or more difficult. You can choose to have students write the color of the correct answer on a sheet of paper and hold it up, or to select a student to give an answer.

Teaching tips

Students who have difficulty adding to 50 can first work on adding to 30. Use of manipulatives like erasers, blocks etc can help make the numbers visual for them. They can also make use of the number line.