This PowerPoint was designed as a comprehensive overview of a 9th grade ecology unit for students to review in preparation for the Pennsylvania Biology Keystone test. It includes a table of contents and 100 slides with button navigation so that students can go through it on their own, at their own pace. Main topics include: (1) What is Ecology?; (2) Ecological Interactions; (3) Nutrient Cycles; and (4) Human Influences (including Human Population, Energy & Natural Resources, Climate Change, etc.) PowerPoint animations are used throughout for pacing and to guide students through the presentation. This could be used as is or divided into parts as a multimedia supplement to the normal textbook.