translation.en: But when you let students work at their own pace -- we see it over and over again -- you see students who took a little bit extra time on one concept or the other, but once they get through that concept, they just race ahead.
translation.zh: 但是当让学生按自己的步调学习的话， 我们不止一次的看到， 你会发现在 某章节上费力的学生 他们一旦攻下了那个概念， 就会后来者居上。