^^^ This
I'm speaking from own experience that the right teacher can do miracles to teach his/her students what they need to know (and more) I've seen people who used to suck at a subject for one teacher, florish in it with another teacher.
Longer school years doesn't solve a damn thing. The last weeks of school even I have a hard time trying to focus on my actual work and need some time off.
Also LBJFan, Finland doesn't have year-around schooling (I don't know about Estonia and China) so I don't really think that has to do with their kids being better at math
