Venn diagrams and apostrophes

I am a very happy mum. This week Elf (5) has been learning about Venn diagrams. I am obsessed with Venn diagrams, believing that everything in life can be expressed in terms of a Venn diagram. I even have a book of song title expressed in these simple closed curves drawn in a plane. 

I am also in amazement still at my son's first visible use of an apostrophe. And it was correct! His dad at 40 still can't get the hang of them, so you can imagine how my heart burst with pride.

Now I know you will fall into one of two camps. Camp 1 = I have no idea what a Venn diagram is and I don't understand or care about apostrophes. Camp 2 = so passé now, but I bought Eats, Shoots and Leaves, and gets annoyed at greengrocers' apostrophes (I even blogged one from Waitrose!).

The picture above shows Elf writing Erin's house. It's not very clear, for which I apologise, but it is there. My heart swells.