Dr. Math was interested in how children learn multiplication. Dr. Math recruited 54 second-graders who had not yet been taught how to multiply numbers to participate in a study. Dr. Math was curious as to whether different methods of instruction would lead to better mastery of the subject. Some students read a chapter on multiplication from their textbook. Other students watched a video of cartoon characters explaining multiplication. A third group of students were taught multiplication by a teacher. In all conditions, participants spent 30 minutes learning the fundamentals of multiplication with one of these three methods of instruction and were then given the same 15-question multiplication test. The number of questions answered correctly was recorded and was used as a measure of multiplication ability. Dr. Math obtained the results in the table below and concluded that the math instruction type affected learning of multiplication. Textbook Video Teacher Number of problems 8 correct 10 13 1. Identify and clearly label the independent variable(s), dependent variable(s), and a control variable in this study.
2. Explain how Dr. Math's study meets the covariance rule for causality AND the temporal precedence rule for causality.
3. Write a question that you would ask to interrogate the internal validity of Dr. Math's study and explain why this questions addresses internal validity.