Inversion Sitting with Heel Down
By having my client stabilize his foot on the floor, I get less cheating with hip flexion and hip external rotation as I try to isolate inversion. Place the target carefully. Often I will passively take the foot to the child's end range position to see how much movement is possible to help guide me in target placement. Alternately you can start with the target very close to the foot and work progressively farther in for stronger inversion.