How can I change the group ownership of directories and subdirectories the easy way?

Hi, I’m trying to change the default group of a directory and about 1200 subdirectories, is there a simple way to do this? The problem is that when I created directories for students the students have read/write priviledges to the folder, the staff group by default has read only. I created a group Faculty and I want to give this group full access to the student files. Workgroup manager only allows me to change one at a time!

Thank you for your help.