New
New
Year 1

# Find a missing part when one part and the whole is known

I can find the missing part when the other part and the whole is known.

New
New
Year 1

# Find a missing part when one part and the whole is known

I can find the missing part when the other part and the whole is known.

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## Lesson details

### Key learning points

1. Each of the numbers one to five can be partitioned into two or more parts.
2. If one part is known, the other part can be found.
3. Know what to do when the known part is zero or the missing part is zero.

### Common misconception

Children may add the whole and one part to find the missing part.

Encourage the use of the stem sentence ___ is the whole, ___ is a part and ___ is a part, to reinforce what the numbers represent.

### Keywords

• Partition - Partition means to split up a whole into parts.

• Part-part-whole model - A part-part-whole model is a pictorial representation that shows the whole and its parts.

• Missing part - A missing part means one of the parts that cannot be seen.

Essentially children will be subtracting a part from the whole here, but do not use 'subtraction' at this stage (or 'take away' or 'difference') as these are introduced in subsequent units.
Teacher tip

### Licence

This content is © Oak National Academy Limited (2024), licensed on Open Government Licence version 3.0 except where otherwise stated. See Oak's terms & conditions (Collection 2).

## Starter quiz

### 6 Questions

Q1.
Is 5 the whole or a part?
Part
Q2.
Is 1 the whole or a part?
Whole
Q3.
What is the whole?
1
2
3
Q4.
Sofia has 1 counter and Jun has 2 counters. Which part-part-whole model is showing their counters?
Correct Answer: An image in a quiz
Q5.
Which part-part-whole model is showing Sofia’s objects correctly partitioned?
Correct Answer: An image in a quiz
Q6.
Which part-part-whole model is showing Jun’s objects correctly partitioned?
Correct Answer: An image in a quiz

## Exit quiz

### 6 Questions

Q1.
How many cubes is the whole made up of?
2
3
4
Q2.
Sofia has 3 counters and Jun has 2 counters. Which part-part-whole model correctly shows the parts combining to make the whole?
Correct Answer: An image in a quiz
Q3.
How many cubes are in the missing part?
2
3
4
5
Q4.
Sofia thinks the missing part will be 3. Is this correct?
Yes