Best small upright vacuum?

My 7 y/o daughter is a cleaning nut. She is a great helper around the house. When she was smaller she had a toy dirt devil vacuum that she loved but outgrew. She has been trying to help me use our regular upright vacuum but it is too large for her to maneuver. So I am looking for a smaller lightweight upright for her to use. Was also looking into the possibility of it being battery powered so she didn't have to worry about a cord. Does anybody have any suggestions?