“Pitting the learning of basic knowledge against the development of creative thinking is a false choice.  Both need to be cultivated.  The stronger one’s knowledge about the subject at hand, the more nuanced one’s creativity can be in addressing a new problem.  Just as knowledge amounts to little without the exercise of ingenuity and imagination, creativity absent a sturdy foundation of knowledge builds a shaky house.”

     - Peter BrownMake it Stick

I believe the most powerful math learning takes place in small, incremental steps with consistent, meaningful reviews. Therefore, I recommend that the first 45-50% of each math class be devoted to fluency and problem solving that covers previously learned topics. I think that the lesson itself can last any amount of the remaining class period so long as teachers are delivering frequent informal assessments and students are receiving meaningful practice.