In comparison to the snatch and clean, the jerk is theoretically the simplest of the three lifts. For the jerk, as in the snatch and clean, certain parts of the body have to move out of the way of the bar so it can travel up straight. In other words, these parts have to move around the bar. In the jerk, of course, the head is the only obstacle. Also, the distance from the shoulders to overhead is much shorter than that from the ground to the shoulders or the ground to overhead.
• Set up in the front-squat rack position with upward pressure on the end of the elbows.
• Head neutral and feet in a stance of flexibility.
• Dip slow, straight and short.
• Aggressive change of direction and exaggerated head movement back while maintaining upward elbow pressure.
• Hips and ankles open completely as chin is lifted to its highest point.
• As the bar begins to float, it stays in the fingertips as it is guided back slightly and the hips start to drop straight down and the feet split.
• The bar and head will quickly pass each other, at which point the hands will wrap and push the body the rest of the way under for a lockout that will occur immediately after the feet return to the floor.
• The bar is now directly over the shoulders and the hips with the head poking through to the point where the ears are just in front of the arms.
• The front foot moves back first to the point where the back foot will step up and meet in the middle to complete the lift.
Full article here: http://library.crossfit.com/free/pdf/CFJ_Jerk_Vaughn_FINAL.pdf
Build to a heavy single from the rack
80 Double Unders
21 Push Presses (115/85)