Random Generator

Not sure if this can be done with Excel but let me explain what I need.

I have an Excel file with the following columns:

LastName
FirstName
ID
Grade
Room
Testing

I have to give a day long test for a campus of 2500 students. All of the 10th graders will be testing and only the 9th and 11th graders that sign up. The Seniors will not be testing. So I have to rearrange everyone's schedule. I have a certain amount of rooms set aside for the testers.

What I would like to do is be able to just generate the 10th graders and the other testers to automatically be put in rooms with no more than 25 a piece.

For example: If I have rooms 240 - 255, ( I know that is not enough rooms_just an example) I want to be able to click a button and they are assigned randomly.

I have a user form made that I can look up the students when I need to find them. I am attaching the form with this post. I hope I made sense of what I want. If not I will try to explain better when someone asks. Thank you.