_____ are factors that are not tested and remain constant.
A. Dependent variables
B. Controlled variables
C. Independent variables
D. Constant variables
The correct answer is D. Constant variables.
Constant variables, also known as constant factors or constants, are factors in an experiment that are intentionally kept the same or unchanged throughout the experiment. These variables are not tested or varied, they remain constant and act as a baseline for comparison.
Constant variables ensure that any changes observed in the experiment can be attributed to the independent variables being tested, rather than any other external factors. By holding constant variables constant, it helps to eliminate their influence on the dependent variable, which is the variable being measured or observed in the experiment.
For example, let's say you are conducting an experiment to test the effect of different amounts of fertilizer on plant growth. In this experiment, some possible constant variables could be the type and species of plant being used, the amount of sunlight the plants receive, the temperature, the humidity, and the soil composition. By keeping these variables constant across all groups of plants being tested, you can be confident that any differences in plant growth can be attributed to the varying amounts of fertilizer used.
In summary, constant variables are factors that are deliberately kept the same throughout an experiment in order to isolate the effects of the independent variable.