Four rounds for time of:
Over Head Walking Lunges x 20 steps
Toes to Bar x 15 reps
Warm up properly and then load accordingly. These should be 3 heavy reps. It should feel around the 4th set, that the second rep is very difficult. You should need to take at least 2 minutes between sets, if not then you need to increase the load. Do not be afraid to fail on the lift. That is what makes us stronger. This however does not mean that you do whatever it takes to complete the lift. Your mechanics are most important. the coaches will be walking around to watch form, but also have your partner help you out and encourage. These should be very taxing on the nervous system, but done correctly, the back squat has astronomical benefits to overall conditioning.
For a little more in depth view of the back squat and bar positioning, click here