We didn't go into much detail, but we talked about who Christopher Columbus was and what he is known for. We made ships out of egg cartons, play-doh (to hold the toothpick in place), a toothpick and post-it notes cut in half vertically (wrap the sticky end around the toothpick). I assigned a ship name to each of the boys (Nina, Pinta, and Santa Maria) to remember and quizzed them periodically throughout the day.
We also made binoculars from toilet paper rolls and the kids went "exploring" throughout the house to see what they could discover. It was raining outside today so we weren't able to do this activity outside. I love listening in while our children are playing. I overheard one of the boys say he spied an octopus. Too funny!
Enchanted Learning also has ideas for more projects. This is one website I subscribe to for homeschool activities and worksheets. This is where I downloaded the world map.
I also found this rather short (3 min) video on National Geographic Kids which might be helpful for those children who are a little more attentive.