This document describes a technology enhanced textbook (TET) being developed to promote active learning. The TET allows students to conduct experiments using sensors on mobile devices, participate in virtual experiments, and communicate with other students online. Focus groups provided feedback that informed the development of the TET's toolbox, communication, and portfolio functions. Learning scenarios involve using sensors to measure sound speed and centripetal force. Virtual experiments let students interact with realistic lab simulations. A portfolio lets students store experiments, virtual labs, and other content to build individualized textbooks. The goal is an interactive textbook that stimulates curiosity and active learning through physical and virtual experiences.