3. Three redwood trees are kept at different humidity levels inside a greenhouse for 12 weeks. One tree is left outside in normal conditions. The heights of the trees are measured once a

week.

IV humidity levels

DV height

CG tree left outside

This question is asking to identify the following:

Independent variable: Different humidity levels

Dependent variable: Height of the plant

Control group: Tree left outside in normal conditions

Controlled variable: same time of measurements (once in a week), same types of trees

Explanation:

Independent variable is the variable that the experimenter changes or manipulates in an experiment. In this experiment, three redwood trees are kept at different humidity levels. Hence, the independent variable is the DIFFERENT HUMIDITY LEVELS the redwood trees were kept at.

Dependent variable is the variable that is measured in an experiment. It is the variable that responds to the changes made to the independent variable. In this case, the HEIGHTS of the trees measured is the dependent variable.

Controlled variable or constants are those variables that must be kept unchanged throughout the experiment for all groups. In this experiment, the constants are: same time of measurements (once in a week), same types of trees (redwood).

Control group is the the group in an experiment that does not receive experimental treatment. In this case, the group that does not receive treatment/control group is: Tree left outside in normal conditions.