At that price range, and without any other specific instructions, it is almost certain that the students will be expected to have the kit lens (18-55mm or 18-[something slightly longer]) that often comes with a new crop-sensor (APS-C or DX) camera. Apart from the slightly inconvenient fact that Nikon users will have a slight advantage over Canon users in the gallery, where wide angle can be important, while Canon users have the edge with the model shots, that will put all of the students on an equal footing, allowing the instructor to teach a class rather than a group of individuals, with the only extra burden being the requirement to know enough about both the Canon and Nikon menus, etc., to be able to help the fat-fingered when they've accidentally set something wrong.
No, the kit lens isn't "the best" lens for any of these uses over the long term, but it certainly is an adequate lens, and what's more, it will allow the student to get the most out of the class. Being stuck with a "nifty fifty" in an area where you need to step back twenty paces (which would mean walking through a wall) will not offset the fact that it will give you better bokeh in a tight portrait-type shot, will it?