What happened
During a demonstration of short-field landing techniques, a flight instructor sitting in the right seat was accompanied by the aircraft owner. As the aircraft touched down on the runway, it encountered a dust devil/whirlwind.
The rotational force generated by the whirlwind made controlling the aircraft difficult due to its low forward speed. The instructor pilot chose not to perform a go-around. Despite the application of both rudder and differential braking, the pilot could not prevent the aircraft from departing the side of the runway. Upon leaving the paved surface, the aircraft entered soft, sandy terrain, which caused it to nose over onto its back. All occupants were not injured.