The rate at which students begin to comprehend and produce a second language is totally dependent on teacher-controlled issues save three: student motivation, student work, student “ability”-level.   

Therefore:

If all of the students in the class are equally motivated,
      (and teachers assume that they should be)

If all of the students in the class complete the same work, 
       (and teachers assume that they should have)

and

If all of the students in the class are perceived to have the same academic skill level, 
    (and teachers assume that students are either "teachable" or "not teachable".)


then they will all accomplish/learn the same material at the same rate.

Therefore:

those who do as requested/planned will earn A’s and those who do not will earn F’s.

and

those who do as requested/planned and do NOT earn A's are less intelligent than those who receive A's,

and

students who have earned A's will know more and be able to produce better language than students who have earned F's.

 
Although I thought so for many years..................none of the above is true.

with love,
Laurie