We worked through student questions about Lesson 20 for the first part of class, with several of the questions guiding students through the learning the textbook intended to introduce through the Salty Eights game in Lesson 21.  Rather than play the game, students instead used the last part of class to begin working with molecular modeling kits (something they will be introduced to later in the textbook).  Although we did not use it today, the Lesson 21 PowerPoint is available for download.  We will work through portions of the Lesson 21 worksheet tomorrow, playing the game at the beginning of class.