On Friday, I taught my economics of education students about "value-added models" for measuring teacher quality. We discussed their pros and their cons.

Then I got the following marvelous e-mail from a student (very lightly edited):

"In my country, it is extremely difficult for younger and inexperienced teachers to have a good ranking compared to relatively older teachers, for to the following reason."

"Before we enter school, some of the parents will donate the school some money or let people who are pretty powerful call the headmaster in the school to make sure they take care of you."

"There are a fair number of parents who do this and all of these kids will be arranged into one class and have the most experienced teachers for that class in terms of every single subject."

"And the teacher evaluation system in my school pretty much only depends on the final exam grade every year and of course these kids who are rich, have more resources already win at the beginning, and will continue to win more dramatically due to the fact of “extra care”."

"Younger teachers however, do not have access to these students and will be assigned to other students and the final results for sure cannot be as good as those special classes no matter how hard the teacher works."

"Thus, I think this VAM method is a really fair system to compare personal progress and I think the teacher evaluation system should be more like this."

"Sorry if this email is so long, I am just really relate to this topic and linked it with my own experiences. Thank you for discussing this amazing topic with us."

That is about the best message a teacher can get from a student. I'll count that lecture as a success.