Subtraction using a Number Line: Counting On Method

This video tutorial teaches subtraction by counting on using number lines and hundreds charts. It explains how numbers increase as you move right and decrease as you move left on a number line. The tutorial includes examples such as finding the difference between 8 and 20, calculating remaining flowers in a garden, and determining gumballs left in a machine. The lesson emphasizes that subtraction is about finding the difference, not just taking away.

What happens to numbers as you move right on a number line?

• They increase.

• They stay the same.

• They disappear.

• They decrease.

How can you find the difference between 8 and 20 using counting on?

• Count back 2 spaces to 6, then 10 more to 16.

• Count on 2 spaces to 10, then 10 more to 20.

• Count on 12 spaces.

• Count back 12 spaces.

If there are 19 flowers and 12 are picked, how many are left?

• 5

• 7

• 9

• 11

How many gumballs are left if 13 are bought from a machine with 30?

• 21

• 19

• 17

• 15

What is the difference between 30 and 13 using a number line?

• 16

• 15

• 18

• 17