I guess this has been posted before, but for the people that haven't seen it yet:
You can actually cast a spell from the same school after being interrupted by abilities like: kick, mind freeze, pummel etc.
How it works:
-Cast a spell, for example: Lesser Healing Wave.
-While you are casting Lesser Healing Wave, spam another spell from the same school, like Riptide.
Once you get interrupted, you actually cast the 2nd spell anyways.
From what I've seen it looks like it stops the spell first before it locks the magic school.
This means u have a split second after the interrupt to cast another spell.
This also works with castable spells, like casting Healing Wave and casting Lesser Healing Wave after the interrupt.