This Teacher Guide is intended to supplement the Teacher and Student Materials for Unit 1. While the Teacher Materials support teachers with what to do, this Guide tells them why, so that enactment decisions are informed by an understanding of the pedagogical approach; we believe this supports teachers to make modifications and adaptations that are aligned with the vision of NGSS. This Teacher Guide also provides additional support with the logistics of enactment, such as pacing, organizing materials, and labs. Routines are embedded into the Teacher Materials; however, this Teacher Guide provides more detailed information about when, why, and how to enact each routine.