1. View the animation on this website:
   
   http://www.cellsalive.com/howbig.htm
   
   To zoom in on the head of the pin, click the arrow to the right of the word Magnification. At 200 micrometers a human hair and massive dust mites surround a tiny speck of pollen. You can move your mouse over the list of items on the right to help identify what you are seeing. If you click on an item in the list, the magnification jumps to where that item is clearly visible. But to get the clearest sense of the relative sizes of the items, use the arrows to increase or decrease the magnification step by step.
   
   After you have zoomed all the way in to the rhinoviruses at 20 nanometers, zoom back out to the pin. Zoom all the way in and out a couple of times.
   
   Now, describe the size of a dust mite from your own point of view, and then the size of a rhinovirus. What words can you use to illustrate their relative sizes? Next, describe the size of a dust mite, and then of yourself, from the point of view of an observer the size of a rhinovirus.
   
   
2. Write one or more paragraphs comparing a natural ecosystem, such as a pond, with a social system, such as a city or neighborhood. Note differences and similarities in the diction you use for each description. Next, write one or more paragraphs comparing two different natural ecosystems, such as a swamp and a rainforest, or two different social systems, such as a city and a school. Again, take note of differences and similarities in the diction you use.