Hello,
As a social worker and a mom, I fully understand your concern. I highly recommend a video called "Stranger Safety." It was created by Julia Clark (founder of the Baby Einstein Company), so you can be assured that it presents issues of dealing with strangers in a way that is engaging to even young children. My son was 4 years old when I bought the video and he wanted to watch it repeatedly, which was wonderful because it really sinks in the concepts of how to deal with "people you don't know," (it doesn't refer to people as "strangers") AND potentially dangerous situations, even showing in role-play the right response to take in these situations. It also talks about "people you kind-of know," which is a wonderful concept to discuss because most of the time children ARE familiar with the person who may victimize them. It even addresses such issues as personal boundaries and empowers your child to think for himself so he can keep himself safe.
For more information and a way to order this very special video, check out-
www.thesafeside.com
This video was one of the best decisions I ever made in talking to my child about stranger danger and ways to keep himself safe. Your son may only be three but it's not too early to at least present this type of information.
Please email me if you have any other questions about the video or talking to your child.
R.