Teaching Models

Subtraction Facts Through 10

Children learn subtraction in a way similar to the way they learn addition—first, by learning the meaning of subtraction through modeling, and then by learning to record subtraction and find the answers to facts and problems by using strategies. This method is appropriate because addition and subtraction are inverse operations.

For numbers a, b, and c, if a + b = c, then ca = b, and cb = a. However, it is not necessary that kindergarten children understand this relationship.

Children first model and act out “take away” situations such as these: Three children are playing and one has to leave; we have six pennies and spend two; we start with six cubes linked together and break off four. The question for each of these situations is “How many are left?” This “take away,” or reducing action, is the mathematical opposite of the joining, or increasing action, used in addition.

Children learn to recognize that, in subtraction, sets are broken down into two parts. They circle the part of the set being subtracted and place an X over this part.

As their work on subtraction proceeds, children learn special vocabulary for subtraction, such as “How many are left,” “Remove some,” and “Some go away.” Children record subtraction with number sentences by using the minus sign (−) and equals sign (=). They learn to record subtraction in horizontal and vertical forms.

Instead of counting on, as they did to add one or two, children learn that counting back can help them find answers to subtraction facts. They use oral counting and the number line to practice subtracting one, then two, from numbers to 10. Children use manipulatives to model other subtraction facts and situations, mainly subtracting from numbers 10 and less.

Teaching Model: Subtraction Facts Through 10

Houghton Mifflin Math Grade K