Sal Khan: Let's teach for mastery -- not test scores

"In a traditional academic model, we group students together, usually by age, and around middle school, by age and perceived ability, and we shepherd them all together at the same pace. And what typically happens, let's say we're in a middle school pre-algebra class, and the current unit is on exponents, the teacher will give a lecture on exponents, then we'll go home, do some homework. The next morning, we'll review the homework, then another lecture, homework, lecture, homework. That will continue for about two or three weeks, and then we get a test. On that test, maybe I get a 75 percent, maybe you get a 90 percent, maybe you get a 95 percent. And even though the test identified gaps in our knowledge, I didn't know 25 percent of the material. Even the A student, what was the five percent they didn't know?
Even though we've identified the gaps, the whole class will then move on to the next subject, probably a more advanced subject that's going to build on those gaps...And that process continues, and you immediately start to realize how strange this is. I didn't know 25 percent of the more foundational thing, and now I'm being pushed to the more advanced thing. And this will continue for months, years..."

http://www.ted.com/talks/sal_khan_let_s_teach_for_mastery_not_test_scores?utm_campaign=social&utm_medium=referral&utm_source=facebook.com&utm_content=talk&utm_term=education#t-6077