I've been teaching my dog hand signals so if there comes a time where I cant talk he will know what to do. I've always preferred to be silent, knives over a gun. The hard thing though is teaching my wife. She says she wants to learn but she wont ever make time for me to teach her. Its always something she puts off. I have tried to tell her that it will be a useful skill to learn, even right now it would be useful. My dad taught me and my siblings and we loved it. I learned military hand sings from him and it was one of the best tools I learned. It is better to be seen than heard. It was simple to learn and easy to teach. You use the basics and add on to that. You pretty much make your own language, something only you and those you teach would know. It is fun and free to learn. Knife skills are great to learn. I am taking another training coarse this coming Summer and there are so many things you can do.