We had very few ideas sent in but it seems that most pupils went on to the other challenge focussed on $28$: $28$ and It's Onwards and Upwards.

Matthew wrote the following and sent in the picture to go with it:

I used $28$ tessellating crosses, which are on the file. Looks quite cool. The scary thing is, after copying and pasting $28$ crosses (having just made them a random size), I, co-incidentally, couldn't fit any more than $28$ on the page ...

and Emma wrote:

I got grid paper and drew $14$ squares that were touching and drew a line diagonally through every square. I got $28$ triangles because I had $14$ squares and split them in $2$ which made $28$ because $14+14=28$. That is how I got $28$ triangles.