The first step in teaching subtraction begins with “minus 0 facts.” The rule for minus 0 is simply that any number minus zero equals itself. Ways to teach the minus 0 rule can include using a simple number line with the numbers zero through 10 and visualizing how this rule works by counting across to the number and telling students you will take away zero. The children can visualize that there is nothing to take away, therefore, the number must remain the same.
Another simple subtraction fact is the “minus itself fact.” The minus itself fact teaches children that any number minus itself equals zero. This fact can also be demonstrated on a number line from zero to 10. This number line helps children visualize how counting to the chosen number on the number line and then saying that you will take away that number will take them back to zero on the number line.
The “difference of 1 fact” is a simple counting strategy that teaches children to memorize that any number minus one will always be the previous sequential number. A number line is also a good teaching tool to demonstrate this simple rule, as the visualization for children helps them to easily understand this rule. You can demonstrate the difference of 1 fact through the number 10 on a number line. It is important to continue to show the relationship to addition throughout the learning of subtraction.
Fact family cards are a tool to teach children how basic subtraction and addition can work together. Fact family cards are triangular cards that have numbers on the three corners and an addition and subtraction sign in the middle. The cards show that the number from one corner to the other using a subtraction or addition sign will equal the number in another corner.