Circle: this is four challenges each building on the previous one   
The first is a small round sprite that draw a circle by using stamp.     

It uses sin(θ) and cos(θ) which of course is not introduced
to well beyond K2. That doesn't matter it introduces the maths
functions. They need no explanations-stop making maths
something you do to get a mark on a paper but some to use
for purposeful intent.

Move from ‘what’s the point’ to ‘wow that’s easier than doing lots
of turns’. You could throw into the conversation that we will
look at and use later some of the other functions that will help
us make more exiting programs.

The crib sheet here is only for the first challange although in
class I would issue the other three - but only after the
students have had a try themselves.