The instructor elected to use a 2800 to 3200 ft road as a landing strip to practice a landing and takeoff. The instructor had used the road many times before and considered it an ideal practice area. The road had been recently graded, was located away from populated areas, and was at an elevation of about 5300 ft. After demonstrating an off field landing, the instructor began a takeoff to the north. The wind was from 220 degrees at 9 knots. A soft field technique was used during the first 1/4 of the takeoff. The instructor reported realizing a mistake and switched to a short field technique and continued the takeoff. During rotation, the nose gear contacted a grade of dirt with a loud bang. The instructor suspected possible damage and made the landing after returning to the airport. During landing, the aircraft veered left as the nose settled to the runway. However, the aircraft was controlled by using rudder. The pilot reported taxiing with little difficulty until the nose gear collapsed during a right turn.