A pedagogical research institute wanted to test a new method for teaching geometry by assessing whether It helps students achieve higher grades. They decided to conduct a study using A volunteering high school with a total of 750 students At the beginning of the semester, 2 out of the 4 high schools were randomly picked to use the new teaching method, while the remaining 2 schools kept teaching with traditional methods. The first pair had a total of 400 students, and the second pair had a total of 350 students. By the end of the semester, the researchers compared the average scores in the geometry section of the final exam for each pair of schools. What type of statistical study did the researchers use