After reading the instructions, we can identify the independent, dependent, and control variables as the following:
1. Independent variable: The two types of fertilizers that will be used.
2. Dependent variable: How fast the plants will grow with each fertilizer.
3. Control variable: The plants that will not have any fertilizer added to them.
When conducting an experiment such as the one described in the question, we are looking for the relationship between two things.
In this case, we want to see if and how the fertilizers affect the plants' growth.
The independent variable is the factor we change in order to affect something. Here, it is the use of fertilizers.
The dependent variable is the thing affected by the independent variable. Here, it is the plants' growth.
To make sure that the independent variable is affecting the dependent one, we need a control variable.
In this case, we would select a few plants to not receive any fertilizer. That way, we can compare the plants and see if the fertilizer is making any difference.
