We watched the Numberblocks 'Thirteen' episode...

https://www.bbc.co.uk/iplayer/episode/m00029t7/numberblocks-series-3-thirteen

We learnt that number 13 is a 1 and a 3, and that the first 1 is actually a 10!

We learnt that the number 13 is what we call a ‘teen number’. The teen numbers start with a 1. They are made up of 10 and a bit more. In the Numberblocks episode we saw that 10 and 3 make 13. 

We practised representing number 13...

- We realised that we can't make number 13 on our fingers so worked with a friend to show 13.

- We practised writing the number 13 in the air, on the carpet and on whiteboards.

- We used tens frames. We know that when we have a full ten frame that there are 10 ones. We can say ‘ten ones is equal to one ten!’ We know now that one ten and a three means there is 13!

- We also made 13 using Numicon pieces and found number 13 on a number line, looking carefully at which numbers come before and after 13.

Finally we practised making 13 with resources. We counted out 13 objects. We made a group of 10 and found we had 3 left. 13 is one 10 and 3, 10 and 3 make 13.