You do need a comma to indicate possession, but where it goes depends on whether it's one student or more than one:

(1) Our student's biggest thanks go to you. (one student)

(2) Our students' biggest thanks go to you. (more than one student)


A single student has the apostrophe before the s, as in (1), but if there's more than one it goes after the s, as in (2).





PaulM

Many thanks!