Knocking stone

Knocking stone is when you take a big rock and hit it against another rock to see if it makes a special sound. People do this to find out if the rock they're hitting is good for making tools. The sound can tell them if the rock is hard or soft, and if it's likely to break or not. It's like tapping a watermelon to see if it sounds hollow or not. Some people even collect these special rocks and use them for making things like arrowheads or knives. So, knocking stone is like playing a game to find the best rocks for making cool things!