Any ideas on what will probably happen?

My friend who is 18 and 4 of his friends who are 17 went to our high school to play soccer. It was around 10 at night and they were walking around outside the school when they saw one of the windows was unlocked. One of them went over and tried it and it opened. They also tried the door and it was open as well. They entered the school and one of the kids started drawing on the cl room door with markers, then he took a helmet and a fire extinguisher out of the room. Obviously they set off a security alarm and the police came. The 18 year old was taken to jail while the rest went home. Now will the 18 year old get jail time when taken to court, even though he isn't the one that stole anything. Yes he did break in and enter the building. His record is otherwise clean and he has had a steady job for a year, got good grades in highschool, and is registered to start college. He was told that this will help when he goes to court.. True?