Prime numbers. The teacher said what the largest prime discovered so far was:

 

213,466,917 – 1.

 

We need to explain why the –1? The answer is that even numbers are not prime.

2 to any power is an even number.

 

It is good to explain reasons for doing things, preferably before starting the explanations. For example, prime numbers. Instead of starting with the games and sheets to find prime numbers, start by saying that we need prime numbers to help us simplify expressions. Mathematicians like to simplify things as much as possible. Now here are sheets, where you are to find the prime numbers …