Cessna 150, VH-WXS, was conducting dual instructional circuits on runway 17 when Harvard, VH-OVO, gave an inbound call. Cessna VH-WXS was climbing through 300 feet having done a touch-and-go when the instructor in VH-WXS heard the inbound call; he considered there was ample time for the student to continue the circuit for another touch and go prior to the arrival of VH-OVO. VH-WXS touched down near the 17 threshold. The instructor was retracting the flaps and the student was about to apply takeoff power when the Harvard passed about 50 feet overhead and touched down about 40 metres in front of VH-WXS. The instructor in VH-WXS immediately transmitted on the radio that the Cessna was on the runway and rejected the takeoff. VH-OVO applied power and took off. Neither the pilot-in-command nor the student in the Harvard saw the Cessna. The Harvard had performed a fairly steep approach whereas the Cessna had made a normal approach. The Cessna was below and in front, and hidden from the Harvard pilots' view during the final approach. The Harvard was probably in such a position on the final approach that it was also hidden from the view of the Cessna pilots. Significant Factor The following factor was considered relevant to the development of the incident: 1. The pilots in the Harvard did not confirm the whereabouts of the Cessna before making an approach to land.