Not wasting time or effort. An efficient strategy is one we can carry out easily.

Use number facts to solve addition and subtraction problems.

Maths

In this unit pupils will add and subtract 1s and 10s from 2 digit numbers. They will use number facts to add/subtract a single-digit number to/from a 2-digit number. They will use a part-part-whole model to represent addition and subtraction. In the future unit pupils will learn to find 10 more or less than a 2-digit number They will  add and subtract 10 to/from a 2-digit number using number facts

In the prior unit pupils added 3 addends. They used strategies such as finding 2 addends to total 10 or 2 numbers to bridge though 10. In this unit pupils will add and subtract 1s and 10s from 2 digit numbers. They will use number facts to add/subtract a single-digit number to/from a 2-digit number. They will use a part-part-whole model to represent addition and subtraction.

Adding and subtracting ones and tens to and from 2-digit numbers

Alex bought a cake for for 34 p and a bag for for 3 p     How much did he spend altogether? Which part-part-whole model represents the problem?

Sam spent 37 p altogether on a box and a ribbon. The ribbon cost 3 p. How much did the box cost?
Which known fact will help you solve the problem?

Choose the known fact that would help solve this problem. There were 54 cars in the car park. 3 were red. How many weren’t red?

Choose the known fact that would help solve this story. First, I had 75 books on the shelf. Then, 3 fell off. Now, how many books are on the shelf?

Sam’s sunflower was 86 cm tall and Alex’s sunflower was shorter. The difference between them was 4 cm. How tall was Sam’s sunflower. Write the known fact that would help you solve this problem.

Choose the known fact that would help solve this problem. Sam saved £45 and then she saved £4 more. How much money did she save altogether?

Which number would complete the equation that comes next in the pattern?

Use the first part-part-whole model to complete the pattern.

Use a known fact to find the missing number.  34 + {{ }} = 39

Match the correct single digit fact to the equation that it could help solve. 

Sam writes an addition that she can solve using the known fact 5 + 4 = 9      The first addend and the sum both have 6 tens. What could her fact be?

This lesson will soon be taken down.

Use number facts to solve addition and subtraction problems.

Lesson outcome