Question

the passage below describes an experiment. read the passage and think about the variables that are described. giardia is a microscopic parasite that lives in water and can infect humans. dr. sloan designed a drinking straw that contained a filter to remove giardia from water. dr. sloan wanted to know if a longer filtering straw would remove more giardia. dr. sloan made six filtering straws: three that were five inches long and three that were ten inches long. she prepared six one - liter batches of water, each containing 10,000 giardia. then, dr. sloan passed one batch of water through each straw. after each batch passed through the straw, she used a microscope to count the number of giardia that remained in a small sample of the water. which of the following was an independent variable in this experiment? hint: an independent variable is a variable whose effect you are investigating. a dependent variable is a variable that you measure. the length of the filtering straw the number of giardia that remained in the water

Explanation:

An independent variable is what is changed in an experiment to see its effect on the dependent variable. Dr. Sloan wanted to know if a longer filtering straw would remove more Giardia, so she changed the length of the filtering straws. The number of Giardia remaining in the water is what she measured (dependent variable).

Answer:

the length of the filtering straw