[AlanSE]

The ideal conditions to stimulate daydreaming seems pretty obvious to me - sit me down in any class lecture.

Imagine that my mind like a glider. Glider is connected to a Cessna by a tether, but it's a magical tether that can disappear. In fact, it takes me active work to keep it connected, like I'm holding on to the end of the rope with my hands. The plane takes off and I'm following in lockstep about the main subject matter... looking down at the landscape below, to the left, to the right. After a quick climb, and at velocity, I've forgotten about keeping tethered, holy crud, I'm in the air! I want to bank, dive, maybe loop! What's over here? I can catch a thermal and go on forever depending on the landscape, but still often see more appealing currents and need to switch over. Oh wait, where did the plane go?