Flight Instructor with student reported they turned final at a non-towered airport and experienced an NMAC with another aircraft on a straight-in approach which took evasive action to avoid the instructor's aircraft.

Narrative

This event took place in Class E; VFR; daylight conditions. My student and I had accomplished several patterns for landing practice. While on downwind Aircraft Y called 6 mile final on an RNAV approach to the same runway. He was on our ADS-B traffic display. I did not yet have visual contact when we turned base at the usual point. My student announced our position. We both looked right and did not see Aircraft Y on final. No other calls had been made by Aircraft Y. My student announced 'turning final' and initiated the turn. A few moments later we received a traffic alert. I looked behind us and at that time the Aircraft Y asked if we would follow him or he should follow us. At that point I could clearly see him - behind us-in a right climbing turn to avoid us. I stated that we did not see him before turning and did not expect him to be this close in yet. As we were already on final we continued with our approach and he rejoined the final behind us and landed. I reviewed the incident on Fly Sto. We were very fortunate as a collision nearly occurred. Aircraft Y flew the approach at 150 mph ground speed. I did not anticipate such a high speed. When I scanned the final for traffic I believe I failed to see him because of expectation bias. I expected him to be farther out and scanned the wrong area. Also; I try to keep pattern communications brief and professional as I make all required announcements. I typically do not solicit information assuming pilots announce their position especially after making their initial approach known. Aircraft Y did not make additional calls as he approached the airport. We announced our position throughout the pattern and I interpreted his silence as confirmation that our movements were not negatively impacting his straight in approach. We would have extended downwind and not turned in front of him had more communication/coordination (on his part or ours) taken place. For our part we learned about scanning; expectation bias; and collision avoidance by reviewing AC 90-48 E; 90-66C; PHAK. I think that an aircraft approaching an uncontrolled airport where aircraft are in the pattern should not utilize straight in approaches but should enter the traffic pattern as recommended by AC 90-66C 9.2 'Arriving aircraft should...avoid straight-in approaches for landing to mitigate the risk of midair collision.'