preposition

CliveIf it's a student evaluation by a teacher, say 'in'.

If it isn't, what should I say?

Here is the paragraph:

My son is a secondary school (0) student. He goes to school five days a (1) week and studies many subjects at school. Last week I went (2) to an end-of-semester meeting with his form-teacher and sh

in

Its answer is on.
I don't find any result "work (well/ excellent/...) in subject" in Google Search.
Actually, I don't know that when a student is evaluated by a teacher, use "in" or something else.
I only know the preposition going with "subject" is "on".

What do you think of this?

You mean "to be good in something"??
I only know the form: ...........to be good at something.
And in Google, there is no "good in math'' (only "good at math", and it is considered to be the right form)
You can check again.

When you say eg good in math, it sounds a bit like you are thinking of it like a math class. That's why teachers often say it that way.

I checked Google again. Here is the first page of results for "good in math".

About 2,110,000 results(0.22 sec

I don't know why you can find those titles.
I searched, but there is only bout 526,000,000 results (0.24 seconds)
And no "good in math".
But that's fine, If it isn't wrong. I read the links you posted and there seems to be difference between "good at" and "good in".

I would say "He is good at math" rather than "good in math" if I were talking about his ability to do arithmetic, although I might say "He is doing good (or "well") in math" if I were talking about his progress in math class this year.
I see the logic of using "on" in the original post context here.
A teacher might well say "He must work on his reading."

Ok, I thank all of you