Grade 2 · Unit 1: Number and place value

Fact families

Three numbers, four facts.

Families of numbers

Some facts belong together, like a family. 3, 5 and 8 make a fact family. They make two additions and two subtractions.

One family, four facts

3 + 5 = 8 and 5 + 3 = 8. 8 − 5 = 3 and 8 − 3 = 5. If you know one fact, you know all four!

Find the missing number

9 + ☐ = 15. Use subtraction, the inverse: 15 − 9 = 6. So the missing number is 6.

The bar model

A bar can show a whole and its parts. Whole = 20; one part = 12; the other part = 20 − 12 = 8. Drawing a bar helps you see which operation to use.

Maths words

The answer to an addition is the sum or total. The answer to a subtraction is the difference. Multiplying gives a product; dividing gives a quotient.

What I learnt

• I can write fact families.
• I can use the inverse to find missing numbers.