Activities for Families

There are two mental models for subtraction – “take away” or “difference.” Your child should be comfortable with both models. Here is 8 – 5 calculated both ways:

Take away (on the left)

Think of 8 – 5 as what is left after you start with 8 things and take 5 of them away. Start with 8 fingers raised. Next, count aloud from 0 to 5, and for each number after 0 put one finger down. When 5 is reached in the count, there will be three fingers left up.

Difference (on the right)

This model views 8 – 5 as finding the difference or distance between the two numbers. Start with 5 fingers raised. Then count the new fingers being raised, and when there are 8 fingers raised the difference of 3 will have been counted.

This method uses the “counting on” addition method to find the number to add to 5 to get 8.

Mix in problems where a number is subtracted from itself, and where 0 is being subtracted.