Number line subtraction
Number line subtraction involves ‘jumping’ along a number line to subtract two or more numbers from each other. Children should be taught both to solve subtraction number sentence by taking away and by finding the difference.
When subtracting children are encouraged to find the first number in the subtraction number sentence and circle it on the number line. The other numbers in the number sentence tell them how many jumps they need to go along the number line. The number sentence 12-7= could be solved by circling the number 12, then jumping along the number line 7 times. Children should be encouraged to check they are jumping the right away along the number line, this can be done by getting them to think about what the number sentence is asking them to do. If it is an subtraction number sentence the answer will be a smaller number than the starting number. Encouraging children to think about what they need to do and why will help them when number lines are not laid out in the way they are expecting.
When solving a subtraction number sentence by finding the difference children should circle both numbers on the number line and work out the difference between them. This method allows children to count up rather than count backwards. The number sentence 12-7= could be solved by circling the number 12 and 7, then jumping along the number from 7 to 12.