Schools should be allowed to copyright original work created by staff and students, if the staff and students have full prior knowledge that if the findings or the quality of work warrant a copyright, the work is subject to being copyrighted by the school. Also, the students and staff who worked on the project should get full credit in the copyright.
Schools often provide funding for their staff to develop lesson plans, lectures, writings, etc. If they inform staff and students ahead of time that any work they produce may belong to the school, this can be completely legal. Many companies have similar policies, like if a web develop writes a code, the company can claim ownership.
Students and staff that make their own things should be just that, their own. Now, at the same time, should a student or staff member make something and then donate it to the school, then [technically] it's the school's in that case. Unless a school is given permission by the creator to do something with it, they should have no right to do anything at all with it. This is simply my opinion.
The reason why companies can copyright work created by employees is because they fund the research and the work is done on their time. Schools should not be able to copyright work done by students because students are paying to be there and learn. So unless it's a protective measure for the benefit of the students, the school should not copyright it.
You can't require a student to do something in order to proceed and then decide it's legally yours if you like it. Honestly, that's kind of disgusting. If a student wants to copyright something that's an entirely different argument, but a school should not be allowed to cherry pick what it thinks is the best from content generated by somebody else.