Louis' Mirage target system is the best thing going. Interestingly, Louis never tells students they have to take a head shot, but almost all do even when the center chest of the bad guy target is exposed more.
One day when we were at my range Louis let my Granson Austin, then 7 yrs old, shoot the system with "Alvin" his .22 Chipmunk rifle. Punched the bad guy center chest. Louis asked him why he shot the chest instead of the head and Austin said, "It showed up more than the head."
I suppose as we get older, we tend to overthink the problem...