yesterday, after we exhausted all fun factors in C152 (like to be faster than cars down there:) ) we “simulated” blocked rudder and ailerons and tried to control flight by opening doors. Was pretty amazing how precise you can control it just by doors.
(good for us, plane was not equiped with turn/slip indicator so we were not aware doing anything wrong :) )
These things are the fun part of the instructor training 
You can also set the engine power to a value that results in 100-200 ft/min climb, tighten the screw of the power lever, trim the elevator and then use the doors for everything: Opened together they will regulate climb and descent and asymmetrically, they will turn you. If you are very brave and have a big runway (and no crosswind) you can even fly touch-and-goes like that.
There are many such tricks, developed over years of tedium flying piston twins on airways.
The simplest is setting the magenta line to the most sensitive setting then flying it with rudder and elevator trim only.
Next up is to maintain course with differential power and elevator trim.
When you bore of that, try differential cowl flaps.
And finally, put in a tiny amount of right rudder trim, then steer by sticking your hand out of the storm wind (use a glove!)
When you have mastered these techniques for straight and level, use them to turn at waypoints.
what next as a young instructor you needed to go out a bit more! Although I like the technique described.
Flying old Pipers it is nice to have them trimmed and see how long you can fly them just with gentle rudder input – it tells me how much unnecessary control inputs we must make, when the aircraft can perfectly well fly itself.
My first powered flying contraption was an ultralight motorglider, Stratos 300, weighing about 170 kg with a closed cockpit.
It cruised around 100 km/h and in calm air I used to maintain direction using rudders, and to maintain altitude by nodding my head slightly forward or back.
When I was doing my CPL, my instructor and I did a full circuit using just the throttle, the doors and the fore-aft seat adjustment in a C152. Good fun indeed.
“fore-aft seat adjustment in a C152. Good fun” well it could be until the seat doesn’t ratchet in properly…..then it might be a hell of a lot “less fun” lol
If you have ever had the seat come unlocked at rotation (I have…) you’ll be very careful checking the seat lock in the future…
