Flight Instructor reported that during a biannual flight review; the trainee entered into an incipient stall during takeoff and did not extend the landing gear on final approach which resulted in a gear up landing.

Narrative

On Day 0; I was conducting a biannual flight review for Person A in his aircraft; a Mooney M20F. I completed his ground training the previous day over a video conference before the flight in accordance with 14 CFR 61.56; and we had agreed to complete the flight the following day due to conflicting schedules. We decided to meet at the airport for a XA:30 flight on the day of the flight so that we could be wheels up by no later than XB:00. The beginning of the flight was perfectly routine; and we departed ZZZ to the east to complete the required aerial work. Upon completing the aerial work; which Person A had failed to do; I instructed Person A to proceed back to ZZZ so we could complete the necessary landings and finish the required items for his flight review. Upon entering the traffic pattern for the first circuit; Person A demonstrated that he had an understanding and capability to land the aircraft successfully. We made a full stop taxi back to runway XX. I instructed Person A to demonstrate a short field takeoff and landing for the second circuit. Person A displayed some confusion about how to execute the maneuver; so I talked him through the proper execution of the maneuver before entering the runway environment. During the takeoff roll; Person A lacked understanding of what speed to pitch the aircraft for; even after discussing the speed on the ground. After repeated verbal cues to correct the airspeed; Person A failed to do so; which resulted in me having to take positive control of the aircraft to prevent an accelerated stall approximately 300 feet AGL. Once we were safely established in the traffic pattern; I gave control of the plane back to Person A to complete the short field landing. Person A became confused about the difference between a red and green light displayed on the top left corner of the dashboard; I inquired if everything was alright because I could not see which light he was talking about. He told me everything was okay and would perform the landing as requested. He verbalized the before-landing checklist by calling out the required steps. However; he was fixated on the runway itself and failed to check the approach to final for additional traffic; which forced me to take my eyes out of the cockpit and verify no additional traffic. Instead of using a standard traffic pattern; he made a short approach with no dedicated base and final approach segments. When I could fully evaluate the situation and configuration of the aircraft; it was too late for me to grab the controls and execute a go-around. We proceeded to slide to a stop on runway XX. We evacuated the aircraft successfully without injuries to either me or Person A. Rescue services were dispatched to remove the plane from runway XX.As for what I believe are contributing factors to this incident; Person A stated that he had not received any training in his aircraft since his last biannual several years ago; and that he needed this sign-off so that he could complete the upcoming flights; Person A stated he was not used to demonstrating the required maneuvers or procedures. After further questioning; Person A noted that a friend of his conducted his previous flight review and that this flight review was more strenuous than previous reviews. I believe a fixation on getting the sign-off resulted in a failure to recognize the aircraft's configuration. Resulting in a belly landing. As for me; the instructor; I believe my failure to recognize the aircraft configuration came from being distracted by having to clear the base and final approach. Transitioning back to the cockpit quickly resulted in my inability to recognize the landing gear in the up position. Resulting in a belly landing. As for corrective actions; I have already signed up for remedial training in the execution and instruction of complex aircraft; with an emphasis on identifying potential hazards and distractions that could lead to hazardous situations. Additionally; it should be emphasized that training is not simply a one-time occurrence every two years; we should all strive to be the best aviators we can be by developing a training regimen with a local flight club or school to maintain critical skills.