Explore +Four is saskatchewan developed approach to math instruction that maximizes engagement. It is predicated on the principle of differentiation so any student at any level can participate in this model. This approach is carried out through rotating stations, that groups of students spend 10-15 minutes at each. Each station approaches the content in a different way so that a variety of multiple intelligences are appealed to. It takes two periods to complete a lesson.
I have spoken with a number of teachers have used it and they all say that each of their students are having more fun with numbers and have all become stronger math students in the process. The students I have spoken to say they hope to never have to do math class the old way again. The students that hated math before love it now!
Start here with a google doc presentation that gives the basics on how Explore +Four works.
Then download this PDF Document that gives a more in-depth explanation behind the process of Explore +Four in Q&A format.