Don’t Touch the Power
Be sure to teach your students to level off from climbs and descents in a quick and efficient way. When leveling from a climb the best procedure is to go about 50 feet past the desired altitude before you do anything. Then lower the nose to level flight on the AI, and hold it there. DON’T TOUCH THE POWER! Leave it at climb power (wide open in most trainers) while making a gross nose-down trim movement to relieve most of the forward pressure on the yoke. When the airspeed reaches the expected cruise value reduce the power to the cruise setting. Finish by fine-tuning the trim. That whole sequence takes 10 to 15 seconds as opposed to the 2 or 3 minutes of fiddling with power and trim it takes if you initiate the level-off by first reducing power.
An efficient and work-free level-off from a descent can be made by figuring out your level-off lead altitude by taking 10% of your rate of descent and at that point simply return the power to wherever it was before you reduced it to do the descent. Don’t apply any backpressure to raise the nose; it will come up all by itself and level off at the desired lower altitude. For example, let’s say you’re doing a non-precision approach and are descending to the MDA at 800 fpm. 10% of 800 is 80. At 80 feet above the desired altitude you promptly advance the throttle back to previous level-flight setting. The airplane will descent the last 80 feet as the nose comes up and you will be in level flight going the same speed as before the descent, assuming you didn’t monkey with the trim. I didn’t learn the easy way to do level-offs until I was in instrument training, but now I teach those procedures to all students from the very beginning.