I was introduced to the three-act lessons of Dan Meyer during my time at UMASS, and I recently saw this Ted talk of his in which he gives some great insight into what math instruction should look like in order to promote student engagement and retention of content.
Fun probability lesson
I just came across these two great dice games to play with students to look at some basic probability concepts. It looks like a fun an informative activity, as long as you add on an appropriate debriefing at the end.