About This Resource
Quick, engaging activities to start lessons or challenge students.
Number Detectives is a projected activity for recalling number types: odd/even, prime numbers, multiples, factors, and more. Pupils follow 4 instructions, crossing numbers that match the criteria on a 1–25 grid (pre-made or self-drawn). The remaining unshaded numbers are added to produce a final answer. Fully interactive: you can cross out numbers on the board and check solutions with the class.
Topics Covered
Mental arithmetic.
Curriculum Links
This resource supports the UK National Curriculum across key stages:
- Number: Properties of numbers, factors, multiples, primes
- Reasoning: Following instructions, checking solutions
How to Use This Resource
Access and Project
Click the button above to open Number Detectives in a new tab. Project the 1–25 grid on your board.
Give Instructions
Read out the 4 instructions. Pupils cross off numbers that match each criterion (e.g. odd numbers, multiples of 3).
Check the Answer
Add the remaining unshaded numbers to get the final answer. Use the interactive board to cross out numbers and check solutions together.
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