2. The boy is wondering what to use to clean the microscope lenses. The lens tissue has been
treated to prevent scratching. What should one
use to clean?
Why?
2. The girl is focusing a slide and she is moving the stage up toward the slide.
a) What has happened to the slide?
b) Is this the proper way to focus?
c) Should you focus by moving stage up or down?
d) What happens to a microscope if place at the edge?
e) What should you do to prevent this from happening?

Juan and carol were studying invertebrates in biology. they knew that segmented or earth worms preferred a dark, moist habitat. during this lab, they would be investigating the responses of organisms called planaria or dugesia tigrina. these were simple flatworms that still had a one-way digestive system and a very simple nervous system. juan and carol placed the planaria in a petri dish containing cool, distilled water that was partially covered with black paper. they shined a light on the dish. next, they removed the paper and placed a small amount of chicken liver at one end of the dish. they added a few large salt crystals to the water. finally, they added drops of hot water to the cool water in the petri dish. their results can be seen in the data table. according to their experiment, all but one conclusion is valid.