It's very clean, very nice. The symbols are obvious what they mean.
The only two critique's I can see is that you seem to use the same colours (Green and Blue). Variations are always nice and good practice. Secondly, watch out for using bright high contrast colours against white. I'm mostly talking about the pencil, it's kinda hard to make out.
It's likely others will have more to tell. However, they don't seem that bad to me.
