Students own the copyright in their own work, as a general principle. The University's Intellectual Property Policy specifies the circumstances under which the University may ask a student to transfer copyright to the University.
If you wish to copy, publish, perform, adapt, or communicate work produced by your students, you need to get their permission in writing. An example in the teaching context is copying one student's work to show others as an exemplar. When student exemplars are uploaded to BlackBoard, the permission should be sent to the University Copyright Officer for recordkeeping, and a note on the item added saying “Used with permission of the author”.
If you wish to use student work for other purposes, such as publication, advertising or promoting the University, be careful to obtain the all the specific permissions that suit your purpose.