When students are learning to subtract, they usually have to begin with the concrete and move toward the abstract. If manipulatives aren't available, they can use pictures to help them subtract. Teachers can use pictures to introduce subtraction and demonstrate that subtraction is taking away from a group. Once students understand the concepts of subtraction, they can draw pictures and cross out the pictures that represent the number being taken away. "Little Giraffes" also suggests activities for subtraction with manipulatives.
Another way students can subtract is by using a number line. Students should start at the large number in the equation and then move backward on the number line toward zero based on the lower number in the equation. For example, if given the equation 7 - 2, a student would start at the number 7 and then move backward two times. The number the student stops at is the answer. In this example, the student would stop at the number 5 so five is the answer. If a number line isn't available, use a ruler instead for addition up to 12. "Teaching Ideas" also has a variety of strategies and activities for students to practice subtraction.
Counting up is another strategy students can use to subtract. Students would start with the small number and then count up to the large number. A visual for this strategy would be asking students to tap their pockets when they begin counting in order to keep the small number to themselves. From there they would hold up a finger each time they count up until they get to the large number in the equation. The amount of fingers they are holding up represents the answer. If given the problem 12 - 9, students would keep the number 9 to themselves and then count up to 12. They would hold up a finger when they say 10, 11 and 12, resulting with three fingers being up, so 12 - 9 = 3.
When you subtract two-digit numbers, use base ten. This can be done with or without a 100 chart. Round each number in the equation down to the nearest 10, then subtract these two numbers. Then subtract the two numbers left out when the other numbers were rounded down. For example, if given the equation 36 - 22, take out the 6 so that 30 is left and then take out the 2 so that 20 is left. Then, you calculate that 30 - 20 = 10. After that, subtract 6 - 2 to get 4. Add 4 to 10 to get 14, so 36 - 22 = 14.