In the preceding activity from the unit, beginning biologists discovered that microorganisms are everywhere, so the question follows, why are we not sick all of the time? Class members read and discuss an article in small groups about...

Make pathogens and the body's defense systems come alive for young biologists in a hands-on activity. Investigators model the skin's protection against infection by observing and comparing changes in a punctured tomato and an intact...

Short, colorful movies explain each of the body's systems: skeletal, cardiovascular, digestive, urinary, respiratory, endocrine, skin, immune, muscular, and nervous. Once you've seen the movie, click on the Activity Page link for...

This activity explains what a fever is and how the immune system uses it to try and protect the body against germs. The students then explore temperature further by creating a model of a thermometer and completing a temperature...

This site from the PBS production, Scientific American Frontier "Never Say Die", includes a section entitled "The Clock of Life". It provides a discussion of cell death through shortening of the telomere. A good class activity included.