Here is a number to think about: 12. Name every whole number that divides into 12 with nothing left over. Hands up when you have one.

The hundred square shows three different shading patterns, one after another. Look at which numbers are shaded in each pattern and look for what the shaded cells have in common.

Today we work on one grid at the front of the class together: shade all the multiples of 4, then all the multiples of 8. What do you notice about where the two patterns overlap? Then we'll shade the factors of 36 and count how many there are.

Today we work through these together on the board, one at a time: first shade all the multiples of 3, then all the multiples of 7, then all the primes under 30.

Then the stretch. First look at 6 together: its factors are 1, 2, 3 and 6 — that is exactly four factors. Your job is to hunt for every other number on the grid whose factor list has exactly four numbers in it. Count the factors by hand for each number you try.