Has anyone played pieces in Prokoviev's book "Music for Children"? Its Valse in A major is in Grade 6 syallbus List C this year. I am studying the Rumba Toccata but my teacher has asked me to see if this Valse is more suitable for me as I am not a rhythmist. Do you think I should use this piece as my repertoire? What techniques should I have in order to play this well?

The Waltz quite straightforward really, just keep a good waltz rhythm like a Chopin Waltz, the notes are a bit more modern though.

Yes, I've played it. It's a good piece, try it.

What about the other 11 pieces in the book? Are them above or below Grade 6?

I would say several are easier than the Valse. The March is probably the easiest one. (Grade 4-5).
Others are marginally easier than the waltz, and maybe a couple a little harder than the waltz.
I dont have the book in front of me right now, as I am away from home, but theyre all good fun to play, some with considerable humour.