Materials for use in baptism preparation are rife though there seems to be a lot out there that is, erm, not very useful.
Something good I saw recommended by Director of Mission, Stephen Harrison at the Anglican Schools Office is Unlocking Baptism Preparation. If that name sounds a bit strange, let me put you at ease: they've used the Unlock word simply because it describes a particular educational process the group who write this likes to use. It's very experiential and though written for adults, it could be used in other contexts too.
The material is entirely free and at the very least, well worth a look through to pick up some new ideas... like using chocolate and dirt!
Have a look at this sample bit...