Calling: Sherlock Holmes and Case of The Missing Phone

My friends and I spotted a cell phone sitting on an empty desk. We decided to leave it there until the teacher came in or the student returned for it. A new girl to our school walked in and sat at the empty desk. We were too involved in a conversation to notice the new girl had left the room and the cell phone seemed to disappear as well. The owner of the missing phone came in and looked under the desk, in the desk and everywhere else you can imagine, but no phone. We mentioned seeing it, but this was little comfort to her. Then the new girl came back from the 'bathroom'. Our teacher knew of the missing cell phone and made it clear if the cell phone was not returned, he would ask a cop to go through all our bags. "No questions asked if it's handed over". He said. As we began to glance around at each other, most of us shrugged our shoulders and said OK. But wouldn't you know it, with 2 minutes left in class, the new girl said "I found it!" She didn't say where or how she found it, but I have my suspicions...But that's High School.