Another way that minority students end up being sorted into lower academic tracks are through standardized test scores.

少数民族学生最终被分到较低学术轨道的另一种方式是通过标准化考试成绩。

And this layering of tracks on top of one another is what gives us the sequence of events; when we have one footprint with a second footprint on top of it, we know that the lower track must be older.

轨道的这种层层叠叠给了我们事件的顺序；当我们有一个脚印， 上面有第二个脚印时，我们知道下面的轨道一定更旧。