Concept Tests, which ask students to stop and check their understanding, have been added to nearly every section in every chapter. Interactive Practice Exercises, new to the third edition, follow each Sample Exercise. This edition continues the approach of framing the discussion of chemical principles within environmental, biological, cosmological, and geological contexts in order to make the science more relevant and memorable for students. The COAST (Collect and Organize, Analyze, Solve, and Think about it) problem-solving method is still used in every Sample Exercise, but the steps have been applied more consistently and more often use estimation and prediction making as part of the problem-solving process.