Hair Chalking

I first heard of hair chalking a few months ago, from The Beauty Department,

 and then A Cup of Jo recently reminded me of it again. 

I've been debating on 'streaking' my hair with some sort of fun colour for summer, but I can't decide which one to go for (pink, purple, bright red, blue, orange). I think chalk pastels might be the best way to try out each one... a whole rainbow of options!