You really do not know the Greek if you do not think the word "rod" means to spank! Yes, a Shepherd does use a rod and a staff, but the rod was used to discipline the sheep, and also to protect them from wolves, lions and bears. The staff was used to pull the sheep away from danger, since the hook on the end of a "Shepherd's Hook". So, for a better understanding of the verse, it basically means to correct and discipline your child in order to steer them in the right direction (towards God). Sometimes that requires force. Sometimes that requires a gentle nudge. It is up to the parent to decide which is required.