A recent article on a web security blog has highlighted a vulnerability in QuickTime for Windows. Two vulnerabilities in the software were made public last week but with out a patch to resolve them because the Windows version of QuickTime is deprecated, i.e. it will no longer receive security updates. It may be worth considering the removal of this software as it may prove a threat for schools, it would definitely be worth discussing the issue with your technical support team.
More details on the issue can be found at https://www.grahamcluley.com/2016/04/quicktime-windows/