I was a new MEI practicing engine shutdowns and airstarts with a student in a typical multi-engine trainer and the left engine refused to restart. No big deal, I had landed countless times before with simulated engine failure. My student had done very well with his single engine landings up to that point, so I thought it would be good practice for him to do the approach and landing. He crossed the threshold a little too fast even though I kept telling him to slow down. Then he flared too abruptly and the plane balooned a little. He reacted by adding too much power on the operative engine. If you remember your Vmc factors, you can imagine how the plane reacted. It quickly began to sharply pitch up and roll toward the dead engine. I usually don't grab the controls, but I didn't want to be upside down on the grass!