Lesson 39 introduces students to the concept of space-filling models. The lesson calls for students to use space-filling models which we do not have access to at our school. Rather than continue to use the ball-and-stick models, students instead worked in pairs and used MolView, a free software program available online. Using MolView, students searched for the compounds in the Lesson 39 Worksheet using the search tool. They then visualized the molecules as space-filling models using the van der Waals Spheres option located under the Model tab. Although not particularly helpful, the Lesson 39 PowerPoint is included. For homework, students are assigned questions 3-7 from page 203 of the textbook.