MyHDL and the NEXYS 2 Board/Sequential circuits
Talk about flip flops, starting with S-R flops, then a transparent latch made of two S-R flops, then a D-flop made of two transparent latches. Maybe talk about JK-flops.
History: JK-flops made sense when gates were expensive. Gates have become so economical that D-flops make more sense today because they make it easy to build synchronous logic.
Talk about synchronous logic and state machines.