Can anyone please tell me what number epsiode is it that Arnold and his friends play a joke on another student's science project and almost get caught and have to hide under their teacher's desk? Then she comes in the room and sits there with the boys under her desk hoping not to get caught. Your help would be very much appreciated..thanks....

You can download and watch that episode at http://www.sitcomsonline.com/diffrentstrokes.html and click on Videos!

The episode is called Arnold and Lisa's Mother, it is #152 according to the episode guide. It is one of the complete episodes available to view and download.