Lesson 10 Add and Subtract Within 100

    • Let’s find the difference in our own way.

Warm-up Which One Doesn’t Belong: Tens and Ones

Which one doesn’t belong?

  1. Base ten diagram. 3 tens. 10 ones. The tens do not show each unit of one.
  2. Base ten diagram. 4 tens. 
  3. Base ten diagram. 4 groups of 10 ones.
  4. Base ten diagram. 4 tens, 3 ones.

Activity 1 Sort and Find the Value

  1. Match each expression to a base-ten diagram.

  2. Choose 1 addition expression and find the value of the sum.

  3. Choose 1 subtraction expression and find value of the difference.

Activity 2 Add or Subtract

Find the value of each expression. Show your thinking. Use blocks if it helps.

Practice Problem

Problem 1

Find the value of each expression. Show your thinking.