Teaching Basic Subtraction for Mastery and Fun
Teacher and Parent Tips to Help with Memorizing Subtraction Facts
Feb 24, 2009
Many kids grow to adulthood fearing subtraction and feeling inadequate in math. Perhaps more than any other math skill, subtraction is often blamed. Thus it is imperative that subtraction be framed for students as a conquerable skill as well as a fun activity.
Teaching Subtraction as a Continuation of Addition
It's worth taking the time to convince kids that subtraction is the same as addition, just turned around. Any time a child masters an addition fact, reinforce the companion subtraction fact in fun and conversational ways.
Use walking games to "add two" walking two steps, or to subtract. Have fun with "subtract 1" or "minus zero" to cement these skills early on, since confusion of this type can challenge a child for a long time.
Reinforcing the Language of Subtraction
Students need to be taught that "the big guy comes first" meaning the larger number comes first when writing subtraction equations. Children who are finding subtraction difficult often make that particular error. They aren't well grounded in the concept that the larger number is written first – a quandary which can make story problems a mystery for them. Use the term "difference" and "how many left" for the answer regularly so children absorb it into their math language.
Remind students often that subtraction makes things smaller. Demonstrate taking away items from a child while verbalizing a subtraction sentence. Clarifying this early in the development of subtraction skills makes learners ready to comprehend the concept of reasonableness of an answer.
Playing Games to Present Subtraction as a Fun Activity
Use edibles (not sweet) like Cherrios, Goldfish, animal crackers, or raisins to demonstrate math facts. This is a great way to have a snack while building confidence in the process of subtraction as just one more way of working with numbers. Kids love Subtraction Snacks.
Use fingers to show simple subtraction story problems in a line or other spare moments. Leader says, "I have 7 elephants and sold 2" while holding up 7 fingers than putting down two fingers. This not only cements the facts, but reminds students that the numbers stand for a word (elephants, crates of apples, etc.)
Use a tens tray to play games to show how to make ten. Manipulatives can be separated into two groups. First make an addition problem to make ten. It can be extended to both ways to make ten. Then play around with turning it into a subtraction problem. Accept any logical answer. This is not a time to push or be demanding; it is a time to develop understanding and reduce fear of subtraction.
Develop Idea of Turnaround Facts
It isn't yet time for fact families. Start with turnaround facts relating subtraction to addition. Take a few minutes daily to work with a partner to say an addition fact, then create a subtraction fact which uses the same three numbers. If this is done for a while, kids will discover that there are two subtraction facts available. This will signal that they are about ready to learn fact families.
Using Doubles to Learn Subtraction Facts
Play Double The Fun: Since your children should already have addition doubles memorized in order to be playing this game, ask a child to say a double addition sentence (e.g. 5 + 5 = 10). Then have another student magically make a subtraction equation using that doubles fact (e.g. 10 - 5 = 5). Play as a whole class, in groups/teams of 4 or so, or in pairs.
To extend the skill, play Double the Fun, Then Take Away One: Someone says an addition doubles fact (e.g. 8 + 8 = 16, so 8 + 7 = 15! ).
Children can learn subtraction without fear by relating it to known addition facts, by using the language of subtraction, experiencing turnaround facts, using doubles to learn subtraction facts, and by having fun to develop confidence in their math abilities.
