Researchers Wanted to Investigate the Relationships Between the Number of Years

Researchers wanted to investigate the relationships between the number of years of school completed, whether students have had primarily male, female, or equal proportions of male and female teachers, and academic aptitude. To encompass as representative a sample as possible, researchers recruited all 6th, 9th, and 12th grade cohorts from each of 150 schools around the country. Using multilevel modeling, the researchers wanted to test the effects of number of years in school and teachers' gender on scholastic aptitude of individual students. How many levels would be present in this design? In your response, be sure to identify each nested level, and provide a brief explanation for why each level would be appropriate. Feel free to provide a diagram if it helps illustrate your response; however, do not substitute a diagram for your explanations.
*note to instructor: do not include this item and item 10 from the multiple choice section in the same exam