Lesson: Relating Addition to Subtraction: Numbers up to 1,000 Mathematics • 3rd Grade

In this lesson, we will learn how to use the relationship between addition and subtraction to check answers to problems with numbers up to 1,000.

Lesson Plan

Students will be able to

recognize that addition and subtraction are inverse operations,
use inverse operations to check answers to addition or subtraction problems involving three-digit numbers,
create addition and subtraction fact families with three-digit numbers using inverse operations,
use inverse operations to find missing numbers in number sentences.

Q1:

There are 511 pupils in a school. If 366 of them are boys, how many girls are in the school?

Check the number of pupils by adding the number of boys to the number of girls in the school.

Q2:

Subtract the problem shown and then add to check your work.

What is the missing number?

Q3:

Perform addition of the problem shown and then subtract to check your work.

What is the missing number?