Where can I get one of those 'Wings Leveller' from?
Could be handy on long flights!
You teach the student to fly straight and level, usually on the second lesson; then you allow him or her to practice this skill over the remainder of their flight training. If you keep touching the controls how will they know if they are maintaining straight and level or you are. The same applies to the rest of the lesson.
If the student is not given the opportunity to learn surely they will take many more hours/dollars to achieve competency