Why do this problem?

This problem requires children to practise basic number operations as well as working systematically. It encourages children to use some trial and improvement to work out what possible options there are and to reason about what the outcome of these different options would be. Choosing which clues to use in which order will help pupils learn how to organise information, identify redundant information and check their work.

Possible approach

As a class, discuss the solutions to these questions, ensuring that pupils are confident with the wording of the problem:

"Hollie is 9 and Tom is 11. Briony's age is half of Hollie and Tom's ages added together. How old is Briony?"
"George is 5 years old. Jess and Alfie's ages added together are double George's age. How old could Jess and Alfie be?"

Explain that in the case of the second question, we are interested in all the possible solutions. If we were also told that Alfie's age was an even number, what would the possible solutions be? What if we also knew that Jess was less than 4 years old?

Display the question about the four children's ages on the board, with the clues. Talk about possible approaches - what could be a helpful way to start? Some children might prefer to read all the clues first, whereas some might choose one to focus on and then move onto another clue. Encourage children to record their ideas and explain their reasoning to each other as they complete the task.

After pupils have solved this question in pairs, bring the class back together. Ask pupils to explain how they know they have the solution. Which information did they start with? Was any of the information not needed? Why?

Key questions

Possible extension

Possible support