How do you present classwork with real companies on a resume?

Hmmmm, it depends on whether the company would consider you working with them, I'd say. For instance, if it were an internship or practicum, I'd list it under the company and call it that. If you didn't really have contact with the company outside the class, I'd list it in details about the class, mentioning the company's names there, or mention it in the cover letter or statement of purpose, etc. Think about it from the standpoint of what the company would say if they were called about your resume. That's a good test of how you should present it.