Solve problems by adding and subtracting tens and ones | Maths

Starter quiz

Which of the following equations are represented by this part-part-whole model?

20 = 3 + 23

23 = 20 + 3 ✓

23 = 3 + 20 ✓

20 = 23 + 3
Which part-part-whole model represents 49 = 40 + 9
The following equations are correct. True or False. 39 = 9 + 30, 39 - 30 = 9, 30 + 9 = 39 and 9 = 39 - 30

True ✓
False
Which of the following completes the equation correctly? 80 = ______ - 4

'84' ✓
Use > , < or = to complete the equation

<

> ✓

=
Use > , < or = to complete the equation

< ✓

>

=

Exit quiz

Which bar model matches this story? There were 43 bees in the hive. 40 of them flew away. How many were left?
Which problem does this bar model represent?

a

b ✓

c
What is the missing number?

'56' ✓
There are 37 children in the park. 7 children are wearing hats. How many children are not wearing hats? Which equation matches this problem?

37 + 7 = ?

37 - 7 = ? ✓

7 - 37 = ?
Tick the problems that will use a subtraction to solve.
Match the problem to the bar model.

A

⇔

Laura had 60 shells. She found two more. How many does she have now? ✓

B

⇔

Jun had 60 sticks. He lost 2 How many does he have left? ✓

C

⇔

Andeep had 66 p. He spent 60 p on a pear. How much does he have left? ✓

Worksheet

Loading worksheet ...

Presentation

Loading presentation ...

Video

Lesson Details

Key learning points

When tens and ones are combined to make a two-digit number, it can be represented as an addition equation.
When a two-digit number is partitioned into tens and ones, it can be represented as a subtraction equation.
We can use bar models to help us understand and represent a problem.

Common misconception

Children may confuse addition and subtraction on bar models and in problems, so may add instead of subtracting or subtract instead of adding.

Cuisenaire rods or strips of paper with numbers written upon them can be manipulated as bar models that represent a problem or equation. This way, the structure of the mathematics can be discussed.

Keywords

Addition - Finding the total, or sum, by combining two or more numbers.
Subtraction - Taking one number away from another.
Part - A piece or section of a whole
Whole - All of something; complete.