omg! found this in my reading 4 hw!

"Clock Crystals: These are the timekeepers for low-level processors. You’ll only need clock crystals if you are planning to use a low-level processor instead of a mid-level module. If you’re using a BX-24, Basic Stamp, or Basic Atom 24, then you can skip this component. They come at a variety of speeds, but 4 MHz is the best place to start for the processors we’ll reference." don't really understand it but love it ne ways.