Talk about stranger danger - i.e. not that all strangers are bad and that greeting people and being friendly is not wrong.  However, because not all strangers are good people, they must never go anywhere with a stranger.  Rather look for security guards or people in charge for help.

The self-defense we are teaching is mainly to get you away from someone who is holding onto you.  For example, someone who is starting to drown in a pool might grab you and start pulling you under too.  You need to get away from them first before you can help them.  The best thing to do when you are feeling threatened is to get away so that is what we are going to teach you.  

Demonstrate each break to the Cubs and then have them practice in pairs.