That risk is fairly easy to mitigate by discussing it realistically at the beginning of the session. That's a risk even in a 6-week series (which I've done before). They simply won't build any new habits in those few hours, but I can give them some new tools to work with.I wasn't going to comment at first as I didnt want to sound disrespectful but since others have said it ill offer my opinion. Doing 1 2 hour class isn't going to teach much I mean martial artists train for years and years perfecting their techniques and moves to be able to defend themselves and learn what they know 2 hours won't be much and In all likelihood they'll have forgotten it in 2 weeks and will give them false sense of security. E.g they'll see something that could be trouble instead of just walking away some may think oh I've done self defence I can protect myself and stay around the danger which could get them hurt.