Q2. At a school there are two different math classes for children of the same age. The two classes have different teachers. The school principal is interested in gauging the effectiveness of two different teaching methods and asks each teacher to try one of the methods. At the end of the semester both classes are given the same test and the results are compared. In this experiment, what is the variable of interest? Give some examples of variables which could be confounding variables.

• What are the response and explanatory variables whose correlation is being tested?
• Explain a method that could be used to randomly assign 20 students to each class.
• Suppose the principal decides to let the parents know about the experiment and lets them choose which class they would prefer their child be placed into. What is the problem with this method of assignment?