Read the text and answer the question.
Lisa: I'm so excited! We're going on a school trip to the science museum next Friday.
Tom: Really? What time are we leaving?
Lisa: The bus leaves at 9 a.m., so we need to be at school at 8:30.
Tom: How long will it take to get there?
Lisa: About an hour and a half.
According to the conversation, when should the students arrive at school?
