Tyler and Elena were asked to find the value of 81 - 79. Their work is shown.
1
What do you notice?
What do you notice?
1
What do you wonder?
What do you wonder?
Grade 2 Unit 7
Lesson 1: Compare, Count on, and Count Back
CC BY 2021 Illustrative Mathematics®
Grade 2 Unit 7
Lesson 1: Compare, Count on, and Count Back
CC BY 2021 Illustrative Mathematics®
Find the value of each expression mentally.
Tyler and Elena were asked to find the value of 81 - 79. Their work is shown.
What do you notice?
What do you wonder?
Locate and label 203 and 198 on the number line.
Find the value of 203 - 198.
Show your thinking.
Locate and label 673 and 680 on the number line.
Find the value of 680 - 673. Show your thinking.
Locate and label 501 and 499 on the number line.
Find the value of 501 - 499.
Show your thinking.
Find the value of 400 - 396.
Show your thinking.
Fill in the missing numbers.
Locate and label 562 and 559 on the number line.
Find the value of 562 - 559.
Show your thinking.
Explain how you know your list shows counting on by 100 and not counting on by 10.
Does this number line show counting on by 10 or counting on by 100?
Fill in the missing numbers.
Does this number line show counting on by 10 or counting on by 100?
Fill in the missing numbers.
Does this number line show counting on by 10 or counting on by 100?
Explain how you can tell your numbers show counting on by 10 and not counting on by 100.
