Hi Teachers,<br/><br/>Is the following sentence right?<br/><br/>"I gave lectures and tutorials <b>on</b> the following areas to <b>classes of 40 to 100 students</b>."<br/><br/>I don't feel comfortable with "on", and feel "in" might match "areas" better, and "on" is good for "topics".<br/><br/>Also, I don't know whether "classes of ..." is the correct way to express the idea.<br/><br/>Any suggestions? Thanks a lot for your time!<br/><br/>Cheers,<br/><br/>Stone.