you could try doing lots of calf raises both on two feet and on one foot (also in passe) to get them used to the idea of going up on to their toes and keeping good posture etc, and as Aussiecoach said get them going through the motions of the turn but without actually turning.
i.e. 1 = stand up tall, toe on knee
2 = knee out to the side
3= bring knee back to front
4= stand up tall on ball of foot
5 = back to flat foot
6 = finishing position - or something along those lines depending on how you teach the turn to look!
regarding stride leaps - they are awful to teach.... but persevere!! my level 3's had shocking ones at the start of the year but I kept making them practice! between hoops, over boxes, onto boxes, simply doing hundreds on the floor... and now they look pretty good (if I may say so

). they are nice and smooth and most actually have pretty near to a full split!
are you doing the 6.00 start value on floor? because the 5.00 start value just need a stride jump/split jump not leaps....