Instructor pilot reported the student and instructor over corrected the controls when the tail wheel aircraft began to pull to left side of the runway. The over correction caused the aircraft to slide sideways and the left main folded under the aircraft. The wingtip made contact with the runway.

Narrative

The student and I were landing in ZZZ. I was on the controls with him but the student was the pilot flying. He had done multiple training flights and landing in the prior months. This was a routine wheel landing. Once we came across the threshold the student pulled the power and worked the plane to the ground. We had one small bounce but added some power and settled back to the runway. Everything was looking okay as we slowed the aircraft down. We then started to pull to the left side of the runway. At that time I added a small amount right rudder to help straighten us out. At that same time I felt the student also add right rudder. This then caused the aircraft to turn ways and begin skidding. I immediately put full left rudder and brake to try and straighten us back out. At that same time I also went full power to try and attempt a go-around. It was too late and the aircraft entered a full ground loop. This caused the main gear to fold up under the aircraft and the left wing tip to hit the ground. We shut the engine off with no propeller strike and immediately evacuated the aircraft. With some help we were able to unfold the main gear and get it off the runway. Looking back at the situation I would have attempted the go-around the minute we started to pull to the left side of the runway instead of trying to straighten us out.