Students own the intellectual property on the work they create in class, but by providing it to the employer they are working with, they give them authorization to use that work for any purpose. Please check out our Terms of Service, under "4. User Data, User Submission, and Privacy" for further details.
If a company and student agree on specific terms for a particular project, this will override Riipen's default terms. For example, students have signed agreements with employers where the employer owns the intellectual property; this may be done if and when the students are working on an employer's existing product. This is the exception and not the norm on Riipen.