Back Hip Turn

Question
I have 2 kids, one 15 and the other 13,that do not get their back hip turned during their swing. They know that they need to pivot their foot but while they swing they just can't execute. While hitting off the tee, they do fine. This causes them use mostly arm and pulls their hand off target Is there a set-up / drills for the back foot pivot so they can "squash the bug"?

Answer
Best way to answer would be to copy an excerpt from the following web page:

揝quash the Bug?  This drill familiarizes the hitter with the proper lower body position at contact (see top photo on the Swing page).

   *
     Front leg straight and angled out front
   *
     Front foot flat and pointed at 1B (3B for lefties)
   *
     Back thigh vertical, upper body directly over back thigh
   *
     Lower back leg bent back
   *
     Back foot on bottom of toes, heel up, pointed toward pitcher (squashing the bug)
   *
     Hips and knees facing pitcher.

Have the hitter just get into this position, so he knows what it feels like.  He should feel most of his weight on his back leg.  Have the player (without the bat) put his right hand (left hand for lefties) out to his hitting side.  Push against his hand while he tries to resist your push.  He should feel how he braces and pushes against his back foot to resist your push.  Then hitter needs to apply this same 損ush?to the bat when contacting the ball.

There are also other useful drills on that web site as well. The fact that the swing is different on the 'T' from live pitching leads me to wonder if there's a fear of the ball involved. Regardless, more hitting practice against live pitching, accompanied by coaching the proper mechanics, should help.

Mike F.