We use Securus and although it doesn't ask before you login, it will bring up a full screen AUP that you have to accept before you can access anything on the computer. If you decline the AUP it will automatically log the user off the computer they are using. Below is a link to the Securus Education website.
Securus Education - Securus
This is the software we have used and it will also provide a monitoring software as well.