Keeping young students engaged

Hi everyone, I'm about to start teaching karate in my village (something I wish I'd started a long time ago!) and the majority of interest has come from parents with younger children (5-7 year olds).

Any advice for keeping them engaged and entertained without having to be too far removed from actual karate? Also, I suspect some kids will enjoy taking up a martial art in the same way many of us did all those years ago, but I'm also concerned some parents just want a cheap babysitter for an hour.

If anyone has any experience with anything like this please feel free to chime in!

Thanks in advance,

Mike