Watch the Number Block episode about the number 4.
https://www.bbc.co.uk/iplayer/episode/b08d61cv/numberblocks-series-1-four
Can you hunt around the house to find the 4 of the same objects.
Think of all the different ways you could make the number 4 - 1+1+1+1, 2+2, 3+1, 2+1+1 etc.
There is a worksheet above is all about the number 4!