This book combines two parts: one is an illustrative story about Tracy's process of learning how avocado seed prevents guacamole from browning quickly. In Tracy's process of knowing why, she has lots of imaginations integrated with experiences mentoring two kids at a San Diego elementary school, and her answers found from the digital dictionary---the Internet. This part uses stories to explain chemistry and relates real life to science. The second part is a letter to its readers for all ages. It uses question-answer sheets and illustration to invite readers to "talk" to their past self or future self.