One thing that is left out the most when training a student to fly/land is whether the student's seat is properly adjusted. I have found that insuring that the seat is at the right height corrects most of the problems during the flare. Adjust the seat so that you can see the top of the engine cowling and almost see the spinner. At this height, you can very well see the end of the runway during flare thus eliminating a touchdown on all three wheels because you can now pitch the a/c to a nose up attitude without losing sight of the end of the runway. Regards.