I had a really good experience last night with some of the local kids. They were playing, and I was playing and losing, until it got dark. Then I started to tell them about Australia. I told them that we have kangaroos. They had heard of them, but I told them about the big tails and how they hop around.
I tried to get them to tell me about some African animals, and after a while we got a list flowing. I tried to tell them that we didn't have any of those animals in Australia, but I think it was a difficult concept.
The night before we had fun playing Dirt Pictionary. This is where you draw a picture in the dirt and people have to guess what it is. It started small, but we ended up drawing over the entire dirt compound where we play. One of the shy boys drew a really good picture of a person. I was quite impressed. We also had flowers, houses, soccer balls (of course), and cups. I think it is a really good idea.
I'm not sure if it is the translation and language barriers, but it seems like children in Tanzania are reluctant to think of answers themselves or to guess. Whenever anyone asks me my age, I try to guess (hoping they will say younger of course), but generally they never guess. The normal answer is just yes.
"Can you tell me how old you think I am?" - me.
"Yes." - local.
It might be just language, but I think it might also be the school system which is almost exclusively focused on memorising information. Games like Dirt Pictionary are a good start.