"If you teach to the stronger students, the weaker ones can't follow. But if you teach to the weaker students, the stronger ones lose interest, nap, do work from their other classes, read fiction, and so on.
張思中自己也很困擾，「照顧好的，差的聽不懂；照顧差的，好的沒勁、要打瞌睡、做作業、看小說。