You had the one with a key? You were lucky. It was madatory in my 8th grade health class, and well, I got the new, more advanced one. It didn't come with a key that you stick in the back. The one I had came with a bottle with a sensor in the tip, 2 diapers (with sensors) so when it would cry, you needed to figure out what you needed to do. Not only that it would get cranky and you would have to rock it and you would have to burp it too.
The first time I took it home, it didn't do anything, so I was like this is easy. Turns out it wasn't turned on so I had to take it home again and I think the teacher made it twice as bad. The thing would cry every 15-30 minutes for like 10 minutes or so. So I'd change the diaper or feed it so it would stop. One time I sat there feeding for like 40 minutes. Burping it was a pain in the a** because it was hard to keep the head up at the same time. But what took the cake was at 2 am it got cranky for 2 hours! My dad came into my room to see me in tears. Yes, I literally cried it was so bad, that thing was h***. My dad ended up taking the batteries out because my parents needed to get up in the morning and couldn't deal with it crying all the time.
The next day I brought it in with the batteries out and tried to explain what happened but the teacher failed me. My parents had to go in and talk to the teacher to complain about the "night from h***" (as they like to call it). My parents said that it just wasn't normal and that real baby doesn't even cry that much. The teacher changed my grade to a B.
Writing about it, it doesn't sound that bad, but it was HORRIBLE! You have no idea..
(sorry it was so long)