Welcome to Litsy!

The authors have updated each of the books eight units to reflect the progress in our understanding of life at many levels, from molecules to ecosystems. The sixth edition has a new chapter that introduces students to science as a way of knowing nature. A new feature highlights examples of the process of science throughout the book, and each chapter contains a process of science question that encourages students to experience science. Media activites allow additional practice with experimentation and analysis of data, and interviews with various researchers humanize science as a social activity.