I have had this a few times
I know it might sound daft but tell them not to land.
Get them to do a couple of circuits and tell them you want them to fly down the runway just above it just above stall. Starting from the aiming point to just after the mid point.
Then once they have that cracked tell them that you will be puting some power input into the throttle and when you do hold the attitude. Then the next time pull the throttle back to idle once they are skimming down the runway and tell them to just hold the attitude. Its not unusal for them to cock up the skimming and land anyway and for it suddenly to click what they are meant to do. Its quite a good exercise to stop ballooning as well.
The point that i used to tell them to start pitching up was when the runway appeared to start moving towards them. Pitch to a almost level attitude while transferring there eyes to the end of the runway. Then as they come down and start trying to skim along the runway take the power off and it will land. And on the cessna 15x and PA38's i wouldn't be to worried about letting them bang it in. Just protect the nose wheel and make sure they don't tail strike by over flaring. You can drop the plane from 10ft up onto its main wheels with no damage apart from the students pride. I used to just laugh when they did it.
As previous poster said the biggest problem is a mind one, if the student thinks that its a huge problem they will start trying to hard. A laugh and a joke is the way forward. A medical neck collar is always good for a laugh. When you brief them don't have it on and when you walk out to the plane have it on.
MJ