We use a graphic to indicate age level recommendations for Primary, Intermediate, Middle School, and High School. Yellow indicates the target age group, shading to blue for age groups which should still find the material usable. Be guided, but not bound , by these recommendations. Some units have Teacher Talk - lesson planning information. Look for the Teacher Talk graphic , which will take you to the Teacher Talk page.
Most units have student activities, indicated by .
The units which have background information are noted by . An activity using image processing software. A virtual walking tour of an urban wetland. Global Change A discussion of this important topic. History of Climate Change Background information.