Understanding Surveys, Experiments, and Observational Studies Practice Test

A district wants to compare two tutoring formats (in-person vs online) for improving algebra test scores. They randomly select 10 algebra classes from the district and then randomly assign the selected classes (not individual students) to use in-person tutoring or online tutoring for 6 weeks. Which statement correctly distinguishes random sampling and random assignment in this study?

A student council wants to estimate the average number of hours of sleep students at their high school get on school nights. They use a random number generator to select 120 students from the school roster and email each selected student a short questionnaire asking, “How many hours did you sleep last night?” Which type of study is described?