Apologia Biology: Biological or Dichotomous Keys

The first two editions of Apologia Biology have dichotomous or biological keys in the first module; the third edition does not.  I like to introduce dichotomous keys.  In addition to the key in the textbook, we use Dichotomous Key Practice with buttons.  The kids build their own dichotomous key with buttons, too.  These buttons work well.  My classes do Alien Dichotomous keys (Answer Key). Identification handbooks use dichotomous keys.  Here is an example.  We do three or four keys, with the button diy key as homework.  Usually, this is plenty.