Minkel, J. (2013, October 17). True Grit.

Part of it has to do with posing more challenges that are complex to our students. If a problem is easy, it’s embarrassing to get it wrong. If a problem is so complex even the teacher has not figured out the answer yet, failure becomes a step toward success. Kids are more likely to spend hours instead of minutes working on these kinds of challenges, because they are worth the effort they take to solve.