Making profit from Arduino
The Arduino itself is open, and you can use it to make commercial products.

Note however, that for commercial products, a lot of additional requirements may be needed (regulations, safety, certifications), especially since it will be used in public places among (many) other people. You don't want students to be injured/die because of a badly designed device. 

Not that I think you might not capable, but it might be something to keep in mind, that your project is maybe more than just creating some software and adding some packages and sell them.