MS-LS4-6 Biological Evolution Population Changes PowerPoint Most slides have animation to keep students engaged. Includes seven slides that students can analyze trends, averages, histograms, graphs, and spreadsheets to identify Changes and Trends, Cause-and-Effect, Increase and Decreases in Traits. MAIN IDEA-Natural selection may lead to increases and decreases of specific traits in populations over time. Disciplinary Core Ideas-Adaptation by natural selection acting over generations is one impo