I was just venting Friday about how when I teach a new concept in my math class the majority of the students do not seem to be listening very well. When I have them start working on their own problems, too many of them need me to re-teach to them. I enjoy doing this but I find that I run out of class time before I can help them all. So my first solution is to pair them up and have a few of my students that "get" concepts quickly help those that tend to struggle.
Then I found a great resource to help on twitter. That Quiz is a math site (and some geography, science, and vocabulary in English, Spanish, German, and French too) that I learned about from @karlyb. It covers many of our math topics and is designed for teachers to make and give quizzes. My purpose will be a bit different. First of all I can have students select specific problems related to our current unit. But what I like about the site is it immediately gives feedback on whether they got a problem right or wrong. This will serve the same purpose as giving students the answers to their homework ahead of time as recommended by Matt Townsley. The problem I have with just giving them the answers ahead of time is that this unit (area, perimeter, volume, surface area) is so easy that it is really just memorize the formula and plug and chug.
Therefore I can have students practice on this site and they can self-assess the areas that they understand and those where they need help. I think I will be using this site as a review tool from now on. Then I can spend my time helping re-teach the concepts that they tell me they need help on.