Basically, I suggest you use an anchor to help keep your consciousness. In class, the teachers voice was your anchor. You simply fell asleep as you listened to his/her voice. This was able to keep you conscious, though the environment fooled you into thinking you were unsuccessful. When you are attempting a WILD, you need some sort of anchor to help you keep conscious. You could possibly turn the t.v. on at a low volume, or play some music on a low volume, or run a fan and use the fan noise, etc. There are infinite number of things you can use as an anchor. Though, and auditory anchor worked for you already, so I would suggest trying that out again. An anchor can coincide with any of the 5 senses. Don't even worry/think about SP much, just try to fall asleep as you keep some attention on the anchor. Once you start to fall asleep, SP will come. Then just remain calm, act as if nothing strange is happening, and just go with it. Continue to fall asleep and you should end up in the dream stat.