A generation ago, after-school tutoring was fairly rare. That's changed. More students now seem to need professional help to keep up with the instruction, especially in math and science courses. Tutoring centers, like Kumon, are proliferating. Affluent parents can pay for private tutors, while in some lower-income districts, publicly financed programs offer after-school instruction. What has changed in teaching approaches or the curriculum that causes more students to seek tutoring? Are science and math courses being taught at too advanced a level?