How do you break down teaching of retire? What is it preparation for?I am thinking it is preparation for pirouette. Breakdown:

facing the barre in a closed parallel position.
peel foot of floor to petit retire (use of metatarsals/foot pressure/correctly)
close and rpt. on the other side.

repeat the above however instead of petit retire, bring toe to the side of knee (before going any further check - alignment, posture, placement, poise, weight distribution).
Take the knee out to the side, return to starting position and close. Rpt to other side.

Try entire exercise with turned out feet.

What say you? any thoughts, comments, observations, idea's would be greatly appreciated.

Is this for adults?

The exercise you mention, bringing the foot to the retire position then taking the knee out to the side, I find invaluable even with the young ones. I also do this ( not with the young ones but around Grade 2 - 3 level) rising to the demi-pointe on the introduction and doing 4 times before lowering.

Hi Tip_toes.
I too do the mentioned exercise for all levels of students. I quite often include the exercise as part of the warm up session before class both as floor work and at the barre. I totally agree with you that it is a invaluable exercise. fantastic exercise for working the turnout too. I agree that level 2-3's plus should be able to handle the exercise on the demi pointe. retire is such a simple step and yet such an important one for many reasons.