Lesson 7 Subtract Two Digits

    • Let’s subtract with two-digit numbers.

Warm-up How Many Do You See: Compose a Ten

How many do you see? How do you see them?

  1. Base ten diagram. 5 tens, 5 ones.
  2. Base ten diagram. 4 tens, 15 ones.
  3. Base ten diagram. 2 tens, 4 ones. 
  4. Base ten diagram. 3 tens, 14 ones.

Activity 1 What’s the Difference?

Students with cards and base ten blocks

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

Activity 2 Use Blocks to Take Away

  1. Choose a player card. Mix up the other cards and put them face down.
    Player name:

  2. Represent your starting number with base-ten blocks.
    Starting number:

  3. Take turns picking a card. Read the card to the group.

  4. Listen for your player’s name. Use the blocks to show the change.

  5. Explain your thinking to your group.

  6. Write an equation to show the new number.
    Equation 1:
    Equation 2:
    My player now has  tens and  ones.
    Ending number:
    Share this number with your group.

  7. Write an equation to show the sum of the ending numbers in your group.

Practice Problem

Problem 1

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