Hemlocks are a common type of tree in the northern forests of the United States. In studying one forest, a forester noticed that mature hemlocks were abundant but there were very few young hemlocks. She wondered why there were so few young hemlocks. By reading the records that other foresters in that area had kept, she learned that the population of deer living in the forest had doubled in the last five years. By reading studies on forests that other scientists had performed, she also learned that deer in similar forests like to eat young hemlocks and the young trees of other species.

To test her hypothesis, the forester set up an experiment. She placed fencing around a group of 15 young hemlocks to prevent deer from eating them. She left a group of 15 young trees with no fencing around them. Each day, she examined the trees for evidence that deer had been eating their twigs and branches, and counted the number of trees with visible bite marks.

What is the independent variable in the experiment described above?

A- the fencing

B- the weather conditions

C- the visible bite marks

D- the deer

(my guess is A)

Thank you!! You are the best teacher on here!! :)

Thank you -- but there are other great teachers here, also. :-)

I know, but you respond to the majority of my question! So thank you! :)

Yes, you're right.

You are correct, the independent variable in the experiment described above is the fencing (option A). The independent variable is the factor that the researcher manipulates or controls in order to see its effect on the dependent variable. In this case, the researcher set up fencing around a group of young hemlocks to prevent deer from eating them. The purpose of this manipulation is to observe the impact of deer presence (or absence) on the number of bite marks on the trees, which is the dependent variable. By comparing the group of trees with fencing to the group without fencing, the researcher can determine if the presence of fencing has an effect on the number of visible bite marks.