Illegal alien students?

just read some community collages will not let illegals into the school this year..someone slap me awake if i am dreaming..if you are here as and illegal alien how can you go to collage instead of being put in jail? this about boggles my brain as to why and how are these things accomplished? i thought they would be arrested if they were bold enough to show themselves daily as and illegal..help me to understand, if any one does..