Lawn first is essential! What it offers is "Angling" with out the fish. Allowing the Angler time to associate him / herself with the equipment. But a key thing here is to instill in the student at that time that this is a practice that is life long!
A cast is like a great painting, book, poem, or anything that requires lifelong duty. How many of our seasond readership still get out the equipment in between seasons, when the river is not producing, or just to spend a few with the kids on a cool spring evening after a hectic day at work, throwing some line. I do! A quick trip up to the local middle school field, or just in the front yard, people may look at you funny at first, but most understand "commitment" when they see it!
Practice makes perfect! If we are to become truley good Anglers, and to teach same, then the practice needs to always be there. This is the sign of a well rounded Sportsman.
I had the pleasure of living next door to Skip Morris some years back. He practices on grass. I think if more "Newbies" were given this instruction along with "How to cast", you might see a higher level of "Maturity" on the river when the time comes.
Hope you all are having a great weekend