unfortunately to teach someone how to use provoke needs:
The tank and party to stand still and listen.
The tank to not get all defensive about it and actually read.
The tank to actually understand what he is reading.

There is no magic universal answer that all can understand perfectly im afraid.

Usually when im healing and i see this i ask the tank if he knows how to use provoke effectively. some admit, some go to a rage, some dont.

most of the times for a party to stop moving is to show them the error. basically let them use provoke and if you are healer time it so you heal the tank at that specific moment. or attack the mob. when you wipe talk to them. Ive had more success in talking to parties after a wipe than before. because before everyone is an Arnold with Stallone crossbreed with a hint of Antonio Banderas but when they die they come to reality.