Addition to 50 with 10, 5, and 1

General

Students learn to add to 50 counting in 10s, 5s, and 1s. They start with the tens, move to 5s and finish with 1s.

Common core standard(s)

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

Relevance

If students are able to add with 10s, 5s, and 1s, they can more easily count large totals.

Introduction

Practice skip counting in 10s with the students. The first student says 10, the next 20, and so on, continue until you reach 100. Restart at 10 and repeat until all students have had a turn. Then repeat this but using skip counting in 5s. Finally show students an image with a bead chain and ask them how many beads there are.

Development

Discuss with students that it is important to be able to add with steps of 10, 5, and 1 to make addition easier and quicker. Show the bead chain and the colored numbers 10, 10, 10, 5, 5, 1, and 1. If you combine the groups of 10, 5, and 1 before adding, you make it easier. Show students the process of beads, numbers, and adding to make the steps clear. Emphasize that it is easiest to start with the 10s, and then move to the 5s, and finish with the 1s. Next practice addition to 50 using steps of 10, 5, or 1 with visual support of balls or figures. Encourage students to not count one by one, but by groups of 10, 5, or 1. Next, students are shown different presentations of addition to 50 with 10s, 5s and 1s, but explain that the process of addition remains the same, they simply don't have the objects to count in these forms. Using the number line, show what the calculation looks like using the steps of 10, 5, and 1. Finally practice a few addition problems that only have the numbers without visual support.

Check that students understand addition to 50 using 10s, 5s, and 1s, by asking the following questions:
- What steps do you take when you add with 10s, 5s, and 1s?
- Why do you not count the 1s first?
- Which set do you add last?
- What is 10+10+5+5+1+1+1?

Guided practice

Students first practice addition to 50 with addition problems with visual support. Then they must calculate with visual representations of groups of objects, and finally they must add with just the numbers given.

Closing

Check that students can add to 50 using 10s, 5s, and 1s by asking them to explain which steps they must take to add using 10s, 5s, and 1s. Discuss that addition goes fastest and easiest when you start with the 10s, move to the 5s and finish with the 1s. Close the lesson with a game. The students are split into pairs. Students will make addition problems by clapping their hands, patting their legs, or tapping their toes. Clapping hands = 10, patting legs = 5, and tapping toes = 1. The first student must create a problem, clapping/patting/tapping, and their partner must solve the problem. Take turns. Challenge: Can they do it with their eyes closed?

Teaching tips

Students who have difficulty adding to 50 using 10s, 5s, and 1s can be supported by practicing with manipulatives like MAB blocks. Have them practice adding the sets of 10, 5, and 1 visually with simple problems like 10+5+1 before moving on to ore challenging problems like 10+10+10+5+5+5+1+1+1.