Just for fun
Self-drilling screws don't require a pilot hole, because they cut their own hole and thread as they are driven into the material using a variable speed drill. You can generally tell which materials they're designed for by looking at the shape of the point and the thread.
Below are four diagrams showing different point styles. Underneath are four names and descriptions.
See if you can match up each screw with its correct name by clicking on the diagram first and then its corresponding name.
