The wonder I am doing is How do Locks Work, #431. In this wonder I learned about to different locks. the first lock I learned about was the Combination Lock, the way this works is When youturn the dial it turns a series of wheels. These wheels have a tab called a "wheel fly. When the tabs line up the lock opens.  The other lock I learned about is the pin-and-tumbler lock (or key lock).  The way these work is they have several spring loaded pins in a series of cylenders, when the proper cylenders are   pushed it unlocks.

combination/set of numbers

valuble/exspensive and important

secure/safe