Solve problems finding a missing part when one part and the whole is known

I can solve problems finding the missing part when the other part and the whole is known.

Download all resources

Share activities with pupils

New

Year 1

Solve problems finding a missing part when one part and the whole is known

I can solve problems finding the missing part when the other part and the whole is known.

Download all resources

Share activities with pupils

These resources will be removed by end of Summer Term 2025.

Switch to our new teaching resources now - designed by teachers and leading subject experts, and tested in classrooms.

View new resources

Slide deck

Download slide deck

Skip slide deck

Lesson details

Key learning points

Each of the numbers one to five can be partitioned into two parts.
Use the sentence, the whole is ___ and one part is ___ so the other part must be ___
Notice the smaller the number being partitioned, the fewer the number of combinations.

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 is one of the parts that cannot be seen.

Common misconception

Children may confuse the part and the whole, or 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.

Part-part-whole models can continue to be used to record and justify answers to problems. Use part-part-whole models in different orientations and with different numbers of parts for children to use to see objects partitioned in different ways.