High School Football Player Was 21

“A 21-year-old man played football at a central Michigan high school after fooling officials with altered documents and an alias, an athletic director said…”

If schools are so secured, how the heck did he get away with using a fake name in the first place? Are they implying that any person can sneak in a school with a fake name?

Source
http://news.msn.com/us/mich-high-school-says-football-player-was-21/