That is because he would have seen her move from the stop line on 3rd to the thin white line and stop again while looking over her left shoulder. (vealelaw.com)
Turn to look back over your left shoulder, using the right hand to deepen the twist. (badassandhealthy.com)
The bottom corner should go up and over the left shoulder of your baby and behind his / her back. (shrewdmommy.com)