Flight Instructor with student reported during taxi the aircraft wing made contact with a lawn mower that was mowing grass next to the taxiway.

Narrative

My student and I landed Runway XX at ZZZ; and exited the runway on [Taxiway] 1. We then began to taxi the airplane towards the ramp to park the airplane. There was a lawn mower off the right side of our wing that was mowing the grass off of the taxiway. The mower than proceeded closer to the taxiway without checking both directions for oncoming airplanes. At this point in time the student was taxiing the airplane and I was debriefing his landing with him; and had my attention focused on the left side of the airplane. My student failed to see the mower; as well as myself; and the wing clipped him. At the end of the day; the situation could have been avoided; no matter who is at fault. It is my job as the flight instructor to ensure the safety of the flight at all phases and divide my attention between the student and the surroundings of the aircraft. It was also very negligent of the mower to not check the taxiway for oncoming aircraft; and at the same time I; as PIC; should have noticed the mower on the right side of the wing. Unfortunately my attention was on the left side of the cabin (my student); and prevented me from noticing the vehicle on the right.