if you can find a naturally occurring chert or flint outcropping, or pick up pieces along the edges of waterway... identifying them to your Scouts might set up a fun project... have a fire building challenge... a fire the way the natives did prior to a ferro rod... there are some large chert deposits, that have now been taken over by an oyster bed, just off shore where I grew up... and as Scouts we were on the lookout for the shiny black or gray pieces...using a piece of char cloth, and the back spine of a carbon steel pocketknife was one of the "extra" skills our Scoutmaster worked with us on... I was lucky to have a couple of dedicated gentlemen in that position...if I remember correctly, we used a shoe polish can with a tiny hole in the top to make and transport the char cloth...the pocket knife and stone in our pocket...probably not politically correct today...