Paleolithic technology

Check out PaleoPlanet.  They have have information on Flintknapping and other "primitive" skills.  In my opinion they are not low level skills.  I suspect most people that study so called "primitive" skills quickly learn that, buy then my BA is in Anthropology.

I think learning "primitive" skills is very rewarding, it is something anyone can learn how to do, though it takes time and effort.  It is an extremely rewarding hobby, activity, or even avocation for adults or children. 

It is an educational activity, part of "experimental anthropology" or term I'm more used to "reconstructive archaeology," were you attempt to learn more about how things were done in the past by using techniques and tools from certain people & time period.

This often leads to new information, you gain knowledge by doing that can not be learned from simply studying the artifacts past people left behind.

Science projects anyone can do with their kids, or by themselves

Crystal Radios are easy to build.  Here is a link to an inexpensive kit from Amazon
here is a link to detailed instructions for making a crystal radio from parts.

So something useful & neat, if your looking for something besides a radio, Science Toys has lots of other projects you can do.  All of it is educational, not just the science, but the skill building and problem solving required to get it right are valuable skills for learning any topic or dealing with real world issues.