Lock the phone in the glove compartment
My son locks his phonein the glove compartment. That way he has it with him and has to stop the car to use it.
I tell friends/family that I will be driving and not to text call whatever. And that I should be free to talk around such and such time. That way I don't even have to think about it I know no one will be trying to talk to me. But honestly the main thing you should teach ALL drivers not just teens! is common sense I mean really, just ask yourself/them do you want to text now (while driving) and eat through a straw loose a limb/limbs possibly not even be able to breathe or make decisions for yourself and never be able to text again or wait and live a good life? Or hit a car with a young couple with four babies and ruin their lives? No you might not wreck your first time, or even the tenth time but the truth is, if you text and drive castrophe (misspelled, sorry) will strike it's only a matter of time.