Adding Columns Of Data In An Aggregate Query

Ok so I need to write a query that finds the lowest grade out of a group of students (by a class number), and identifies it by a student id #.

Here's what I'm trying:

select min(gr.grade), gr.stu_id
from dbo.class cl, dbo.grade gr
where (cl.class = 2) and (abs(cl.stu_id) = abs(gr.stu_id))
group by gr.stu_id

but unfortunetly it returns the lowest grade for each student in class 2, and not the single lowest grade in class 2 and the stu_id (student ID).

I'm new to SQL and could really use the help.

Thanks