Lesson 21 Compare Two-Digit Numbers Shown in Different Ways

    • Let’s compare numbers.

Warm-up Number Talk: Addition Within 20

Find the value of each expression mentally.

Activity 1 Elena and Kiran Compare Collections

Elena and Kiran are comparing their collections. 
Elena says, “I have 5 tens 32 ones.”
Kiran says, “I have 7 tens 2 ones.”
Who has more in their collection?
Show your thinking using drawings, numbers, words, or expressions.

Activity 2 Base-Ten Representation Compare

Problem 1

What do you notice?

Base ten diagram. 3 tens. 8 ones.
Base ten diagram. 2 tens. 8 ones.

Problem 2

Circle the representation that shows the greater number.
Write a number to match each representation.
Then write a comparison statement using <, >, or =.

  1. Base ten diagram. 3 tens. 2 ones.
    Base ten diagram.  2 tens. 12 ones.

  2. Base ten diagram. 2 tens. 15 ones.
    Base ten diagram. 4 tens.

  3. 5 tens 2 ones

    12 ones 3 tens

  4. 1 ten 25 ones

    Base ten diagram. 3 tens. 5 ones.

  5. 7 tens 29 ones

Practice Problem

Problem 1

Fill in each blank with , , or to make the equation true.

  1. 79

  2. 20+25

  3. 35