You own the copyright to the assignments you have worked on yourself. That holds regardless of whether it is a master thesis, a project, an assignment, a model, a source code etc.
You choose, whether you wish to share the assignment with others by consenting to its use.
If you have worked on an assignment in cooperation with others, you have shared copyright to the assignment, and must agree with the decision to share it
If your lecturer would like to use your work as an example for other students by, for example, sharing it on Brightspace, this requires that you give your consent. You decide whether your name should appear in connection with the assignment being shared.
For all assignments upon which you have worked yourself, you own the copyright. This is regardless of whether it is an essay, project, model, source code, thesis, etc. It cannot be made available without you having given your consent.
Some degree programmes at Aarhus University have created document repositories that contain examples of good papers which other students could benefit from reading. If you accept that your work can be uploaded to such a repository, you are thereby giving your consent for the assignment to be made publicly available. This requires particular attention from you with regard to copyright, as it is your responsibility to ensure that the contents of the assignment may actually be legally published.
If your work group has worked on joint notes, assignments or smaller text excerpts, which you have then made use of in another assignment, then you must also specify this in your assignment by making a reference to the source. If you, or others, would like to make use of the material that has been worked on jointly, all co-authors must give consent for it to be used in a new context.
You may use old assignments, for example by using passages in later assignments. However, remember to cite correctly.
The same goes, if your study group has created shared notes, assignments or smaller texts. However, be advised that your co-authors need to consent to for the material to be used in a new context.