The Fowler Museum located on the UCLA campus is one of my favorites for all sorts of cultures. They do not charge admission! It is a museum dedicated to world cultures and the ed staff is wonderful there. I am a guest artist there at times, most recently teaching a class on mask making as it related to an exhibit on the Makishi from Africa. There are two exhibits relating to African art right now. Another great resource is the DeYoung museum in San Francisco. They have an amazing collection from Africa. These are both located in California, but I find most museum educators are very open to send teachers materials and help in way. Here are the links for the Fowler and DeYoung museums.