Book excerpt: Based on the best-selling book The Parallel Curriculum, this resource deepens teachers' understanding of how to use the Parallel Curriculum Model (PCM) to provide rigorous learning opportunities for students in science, grades 6-12. This collection of sample units and lessons within each unit were developed by experienced teachers and demonstrate what high-quality curriculum looks like within a PCM framework. Ideal for use with high-ability students, the units revolve around genetics, the convergence of science and society, the integration of English and Biology, and the Periodic Table. Lessons include pre- and post-assessments.