I recently learned of a fatal accident on a check ride where the applicant incorrectly entered a slip at low altitude. The airplane spun in to the ground killing the applicant and examiner. The only reason the investigators knew the applicant and examiner entered a slip is because it was announced on the radio.
I have noticed several issues with slips. The easiest way to correct some of the problems is to have the student talk their way through the slip. “Lower the wing, opposite rudder” is one verbal technique that works! Each time they enter a slip make sure they say "Lower the wing, opposite rudder. BTW, Slips don’t have to be aggressive or quick, just smooth and purposeful.
"Lower the wing, opposite rudder." "Lower the wing, opposite rudder". Lower the wing, opposite rudder".
Good airmanship tips…lower the wing that is into the wind…Power at idle.
When exiting a slip relax the pressures on the flight controls.
Slips are fun and serve a useful purpose in every pilots bag of tricks!