Is it correct?

I don't know what that means.

It means that it is *** to move smart kids from second class to fourth class because they don't feel boring on lesson.

A survey of the applicable research suggests that the faster that gifted students are placed in grade levels suited to their abilities rather than their age, the higher their academic achievement will be.

Thank you for suggestion but can be it easier. THis sentence is too long and too complicated. Can be something like this: "The meta-analysis of research suggests that faster placed to higher class helps high-ability students achieve success in life, especially with academic achievement.