I really do love Scratch...
It's a nice gentle introduction to coding that does not scare children out of Computing.
Each of the blocks can be built into a sequence that can make a game, an animation of be used as an instrument.
I teach a lot of Scratch at my CPD events and it is mainly aimed at Primary School teachers who need to know how the programming curriculum can be taught.
The most effective way I find is to teach cross curricular and use Scratch as a tool in other lessons. So with that in mind, this morning I spent 20 minutes writing a simple Maths Quiz using Scratch 2.0.
The game will choose a random number between 1 and 12, this corresponds to the times table.
From there the game will ask three questions based on the times table. Each time you play the random number will change and ask three questions (2 X, 6 X and 9 X the random number)
Have a play and hack it to make it your own.
You can find all of the code on Scratch's website