D.C.
My 1st grader LOVES the "The Magic Bus" series. They are set in a classroom with a crazy science teacher who takes them on field trips. For example, the bus full of the kids somehow gets eaten, and the kids learn all about the inside of the body. Or the bus somehow ends up in the ocean and the kids learn all about the sea. It's written in a really silly way that first graders love. It would probably take 20 minutes to read out loud.