Datapointed: I like to start this one at the beginning of the lesson, let them watch up to about 20, then teach the lesson leaving it running in the background. Then come back at various points to see how far it has got.
Primitives: This one is more interactive and can be used when teaching Prime Factor Decomposition.
Chalkface: And finally a blog post with lots of interesting ideas and this nice graphic.
mho maths 