A student wonders, "does the moisture content in soil affect how far a worm can dig?" identify the variables that are being considered in this experiment and the variables that need to be controlled. independent dependent controlled

In this case, the independent variable is the moisture content in soil, since it can be manipulated by the experimenter and it can cause the outcome. The dependent variable would be the depth that a worm can dig in the soil because it can change or not depending on the independent variable. The controlled variable, on the other hand, would be the type of soil that the experimenter will use.