Flight Crew Commercial; Flight Crew Flight Instructor
Flight Crew Last 90 Days 80; Flight Crew Total 450; Flight Crew Type 300
Situational Awareness
Conflict Airborne Conflict
General None Reported / Taken
Human Factors; Airspace Structure; Procedure
I was doing a training flight with my student in the south training area of GPM. This is where we normally go to conduct VFR training flights while at 3;500 [feet] 25 SSW of GPM; over Lake Alvarado; East Side of I-35. We were doing steep turns when I saw a drone almost a size of a computer (Red and White in Color); pass underneath us about 200 ft. low; half a mile of horizontal separation. Since we were already in a steep turn; we didn't have to take any evasive action; but that was definitely a bit alarming. The aircraft is equipped with ADS-B in/out and also I was flying with a potable ADS-B; we didn't receive any transponder signal from the drone.  The drone was on a north heading; and if it had continued that way (which I didn't see after the completion of my steep turn) he would have probably ended up in DFW Class B in another 10 miles or so at that altitude. We call GPM Tower; and reported the incident. Upon landing at GPM; GPM Tower further asked more about the incident and the report is being filed.
CFI reported encountering a drone at 3;500 feet altitude while conducting a training flight.