This makes a good problem-solving lesson when you have been covering place value. Each sheet contains a grid of numbers. Your ‘secret agent’ pupils must use the clues provided to help them to eliminate numbers until only one number is left. This is the secret number!

Depending on how much time you had, you could perhaps make a linked activity where the children have to do something fun with their ‘secret numbers’ at the end of the lesson.

The 4-way differentiation is based on the number of clues, the size of number and the size of the grid the children have to work with. I would suggest working through an elimination grid as a class first, then perhaps using a grid in pairs, before moving to the challenge sheets as a solo task. A final extension or plenary task could be to have the children look at a 3×3 grid of numbers and see if they can come up with their own set of clues.