There are seven dots in all. Two are yellow. How many are not yellow?
There are seven dots in all. Two are yellow. How many are not yellow?
There are nine dots in all. Five are yellow. How many are not yellow?
NOTE: Explain that for each group of dots there is a total number of dots and that the number of yellow dots can be found by subtracting the yellow dots from the total number of dots.
A good activity is to draw a group of empty circles to represent a problem such as 5 - 2 (in which case you'd draw 5 empty circles). Have the student color in the last two circles (representing the two in the problem) and count the circles that weren't colored to find the answer to the problem. Do a few problems like this, especially if you are not convinced that the student really understands subtraction.