Zimmerman got out of his vehicle to follow Martin on foot, though a dispatcher told him that was not necessary. After that, police say it is unclear what exactly happened, but Zimmerman said he no longer saw Martin and was returning back to the vehicle when the teen approached him and they exchanged words. Martin, he said, then struck him, knocked him down and began banging his head on the ground.

thats ONE SIDE of the story. not necessarily the truth. Do you really believe zimmerman would admit to instigating or escalating anything?  During the confrontation zimmerman could have walked away himself or again he have chosen to not follow PERIOD. 

I find it incredible that between a 17 year old and a 28 year old... people expect the teen to act more maturely.