Lesson 7 Compare Methods for Subtraction
Let’s compare subtraction methods.
Warm-up True or False: How many Tens? How many Ones?
Decide if each statement is true or false. Be prepared to explain your reasoning.
Activity 1 Different Ways to Decompose
Diego and Elena drew base-ten diagrams to find the value of
Diego
Elena
Problem 1
Compare Diego’s work to Elena’s.
What is the same?
What is different?
Problem 2
Tyler used equations to show his thinking.
Diego says Tyler’s work matches his diagram.
Elena says Tyler’s work matches her diagram.
Who do you agree with? Explain.
Activity 2 Introduce Target Numbers: Subtract Tens or Ones
We are going to learn a new way to play Target Numbers. You and your partner will start with 99 and race to see who can get closest to 0.
Practice Problem
Problem 1
Here is Mai’s work with a subtraction expression.
What subtraction expression does Mai’s diagram show?
What is the value of the expression?
Use Mai’s method to find the value of
.