Lesson 7 Use Strategies and Algorithms to Add

    • Let’s consider when to use algorithms and when to use other strategies to add.

Warm-up Number Talk: Little More, Little Less

Find the value of each expression mentally.

Activity 1 Just Ones

Two methods of recording the addition of are shown.

Method 1

Addition. Six-hundred fifty-seven plus two-hundred eighty-six equals nine-hundred forty-three.

Method 2

Addition. Six-hundred fifty-seven plus two-hundred eighty-six equals nine-hundred forty-three.

Problem 1

How is the newly composed ten and hundred recorded differently in each method?

Problem 2

Try the second method of recording to add these numbers:

Activity 2 How Would You Add?

Students working with partners in math class.

Use a strategy of your choice to find the value of each sum. Show your reasoning. Organize it so it can be followed by others.

Practice Problem

Problem 1

  1. What do the 1s above the 2 and 5 in 253 mean in this calculation?

  2. Use an algorithm or another strategy to find the value of each sum.