Wallwisher.com might be a good place to have the kids review. They would have to put an answer to the question. Then NO 2 answers could be the same, so the kids would really have to read all the answers so they don't put down the same one. I like it.
Polleverywhere.com is interesting because the kids can use their smart phone to answer the poll instantly in the classroom. You don't have to mess around with active votes if you don't want to take answer grades from individual kids. Kids love to use their phone for everything so this would probably increase participation. They could also make their own polls for other kids to take.
Polleverywhere and Wallwisher are located on the side of blog.