Warning: the how-to video below is a bit odd (in fact you may want to watch it without sound), but the idea is a cute one to do with little ones. I did it with S yesterday and plan to make one each Halloween to watch his spiders grow over the years! Thanks, Julia!
Updated apology: Yikes! I actually took the time and listened to the lyrics of the You Tube demo. I am not very current on rap music. Sorry! Some of you may have thought it was hilarious (S.H.), but others may not have found it as funny so I took it down in case you fall into the latter category ;)
To make the spider you just fold a sheet of black paper in half and trace your child's four fingers (no thumb) on the side with the crease. Then cut it out and when you open it up, you should have eight spider legs!