Since the "student" is outside the Dallas area. The hitting coach should provide info on "self teaching". The "mirror" and the "shadow" are tools.
Of course the "high tee" drill.
At a Area Code tryout in Notre Dame, the White Sox scouts and Scouting Director made a "joke" when the stated that I could tell bat speed over the phone.
Yes, I said. Place the phone next to a tee, use a wood bat and I listen to the impact.