Jenny is very tall for her age, and when she dresses smartly for her first day at a new school, she looks very grown-up indeed. So grown-up, in fact, that when she arrives at the school, she is mistaken for a new teacher, and left in charge of a classroom of kids! Jenny is forced to keep up the act, and soon finds herself in all sorts of tricky situations. Whatever happens, it's going to be a real education!