A math program that endorses drills and pain as the foundational element of math instruction (rather than a supporting element) and as a prerequisite for creative mathematical thought (rather than a co-requisite) inhibits the student and the teacher both, diminishing the student’s interest in producing that creativity and the teacher’s ability to notice it.

Source: Drill-Based Math Instruction Diminishes the Math Teacher as Well – dy/dan

What a powerful statement. Math is a very creative area of study, and without it, the understanding and implementation of math is diminished.