Math With Bad Drawings had a terrific series on how students try to avoid thinking in math class. A quote:
Occasionally, we teachers grow frustrated with our formula-thirsty students. (Okay, more like “often” or “weekly.”) Sometimes, we even denounce formulas altogether, deriding them as “brainless plug-and-chug” or “not real math.”
Of course, that’s going too far. The intelligent use of formulas is an important part of mathematics. But we’re right about one thing: there’s a lot more to formulas than just throwing numbers into a blender.
Here is Part 2, addressing students’ natural desire to mindlessly plug numbers into a formula without conceptual understanding: http://mathwithbaddrawings.com/2015/01/14/mmm-strawberry-rhuburb-root-2/