A Flight Instructor reported their student flying solo temporarily lost control during landing roll due to a flat tire.

Narrative

I am writing a report for a situation that happened with my student pilot while she was on a solo. The student was to do touch and goes in the pattern for 4 laps. At some point; the student's left main tire went flat and she was unable to exit the runway because of it. The student reported that it felt like the airplane was trying to turn on her third landing; but assumed she just needed more rudder and continued. On the fourth and final landing; it turned to the left again and the student slowed down and came to a stop. The left tire was in the grass at this point but the main and right main tire were both still on the runway; and no part of the aircraft or airport property was damaged. She then informed Tower of the situation and received a tow back. The student reported that she thought her first two landings went well; but it is unclear if a possible sideload caused the flat tire. We had a discussion about how; in the future; if she ever sees any abnormalities during a landing then it is always best to just ask for a full stop at that point. The student was unfamiliar with the feeling of a flat tire in an aircraft and did not realize exactly what had happened at the time.