Ride with your eyes closed (for short distances, or on a lounge or in a round pen)
Have student sing a song to help them stay relaxed while riding without stirrups or on loung without reins
Have student call out foot fall (right. Left right . ..) see how accurate they can be.
Practice stopping on a dime.
Ride a buck ( a dollar bill under the thigh of a bareback or stirrupless rider)
Dropping and picking up stirrups during trot