We spent the afternoon at a local park and ended up playing volleyball with a dad, his 3 kids, and 2 of his neighbor's kids (3 teens, an 8yo girl - perfect for Alex, and a 5yo boy). I played for 2 hours!!! I'm SORE, but it was so much fun!!!
Alex also watched a movie we bought several years ago called Our Friend, Martin. It's a wonderful cartoon story of Martin Luther King's life. But, as a warning, there are real clips of his life AND some violent clips showing how blacks were treated during this time. So, be prepared and watch with your child! But, we have both learned a lot from this show and Alex has watched it many times.
Lastly, here is a post I made when Alex was 5 that includes some books we read about Martin Luther King when she was younger.