In this article we provide a simple method parents and teachers can use to teach subtraction to students. The intention of this exercise is to help students understand subtraction as counting back, taking away and difference.
Teaching method for subtraction
What you will need
Construction bricks, marbles, rocks.
- Start by telling the student that you are going to tell them a new story.
- Say, ‘First there were six children playing with construction bricks,’ Place six construction bricks on the table, ask the student to count the bricks to confirm the number of bricks.
- Then, tell the student, ‘Then 2 children went off somewhere else to play’. Remove two bricks from the table.
- Ask the student to tell you how many bricks are on the table now. Confirm that there are 4 bricks.
- Ask the student how they know. The student may say that they counted or could say that they remember that 4 + 2 = 6. There were 6 bricks, but 2 were taken away. Since
4 + 2 = 6, there must be 4 left.
- Remind the student that you told them a ‘first, then and now’ story for addition and
ask how this story was the same and how it was different.
- In the addition story, you added more cars, but in this story, you removed some bricks.
- Explain that what the student saw was a whole of 6 and a part of 2 being taken away.
- Record the matching number sentence 6 – 2 = 4, highlighting 6 as first, -2 as then and 4 as now. Also highlight the minus symbol (-) used for subtraction.
- As with addition, explain that there are different kinds of subtraction. Explain that the student will be concentrating on subtraction as take away, having a quantity and then taking some away and finding out what is left.
- As with addition, check that the student recognises that the number sentence is a way of recording the story, so they must include all of what happened in the correct order: first, then, now. Highlight the symbol for subtraction (-) so that the student is clear about which symbol to use.
