+1 on the gliders. They teach energy management and planning, and finding that next thermal forces you to get rid of the tunnel vision so many people get while flying. I also agree with the high speed on/off scenario. You need to be on your toes and well practiced to land where you want when the plane wants and not be caught with your pants around your ankles. A saying they have in full scale is starting to become appropriate in models, now with the newer better engines and electric motors, "We used to train for when the engine quit, now we train for if the engine quits."