You can invest money in researches to help to expand your university. Tap on the test tube icon to start doing research on your campus! 
 
 
You can open new areas of knowledge, increase their capacity or extend the existing courses. Also, you can do researches in order to earn more money with some tuitions or reduce the service times of your staff.
 
Pay attention to the three tabs in the lower part of the dialog window if you want to check all the researches available (studies, economy, employees).
 
 
Consider carefully which research will benefit you the most in your current situation, as it can help you a lot!