This worksheet is a stand alone worksheet in that no previous lecture has to be done in order to complete the worksheet. I like to show a video first, but it is not imperative. I use the vide "Clone" which is a relatively simple video, interesting and easy to understand. You can add more questions to this worksheet and you can use it as a pre-test. You can make a quiz that looks just like the diagram and have them label the diagram. I tried to make the process relatively easy to understand.