Computer lab: how to avoid installations

[HHH0178]

Hello:

I'm going to have to give a series of courses at work in a computer lab with 20 workstations.
I can manage more or less with a single workstation, but in a network I'm a fish out of water.
What I want, in general terms, is that none of the 20 students install anything or can "mess it up". Just that they can plug in their USB drive to get the exercises and that's it, but nothing about installing or modifying anything on Windows (I wouldn't even want them to change the desktop background).

Can you give me some guidance?
The computers have Windows 7 64-bit

Thanks

[garfield]

It should look something like this:

WinLock - Download

[Nemo]

And what are user accounts for? If I'm not mistaken, by setting up the accounts, they can't install anything, in fact, you can even set it so that they only use certain installed programs.

Best regards.

[HHH0178]

thanks, I think the easiest thing for me (I don't control anything about multiuser) is to create a specific account.

Windows 7 lets me create a standard user account, but how do I give or remove permissions to that account?
I'm very interested in the idea that only certain programs can be used, how do I do that?