The teacher quality conundrum: If they are the problem, why are kids gaining in math?  - NY Daily News

http://www.nydailynews.com/opinion/teacher-quality-conundrum-problem-kids-gaining-math-article-1.986066

If we believe that teacher quality is poor (or at least not any better than, say, 20 years ago), then what explains the long-term NAEP gains in math? Maybe our curriculum is better, suggests Dan Willingham.