Selecting an Experimental Design Practice Test

A researcher wants to compare four study strategies (flashcards, practice tests, rereading, and summarizing) on a vocabulary test. Students’ prior vocabulary level (low vs high, based on a pretest) is expected to strongly affect outcomes. The researcher has 80 students total and can assign each student to only one strategy. Which experimental design is most appropriate?

A chemistry teacher wants to test whether three different lab instruction formats (video demo, written instructions, and live teacher demo) affect lab report scores. There are 3 lab sections meeting on different days (Monday, Wednesday, Friday), and the teacher suspects day-of-week differences (fatigue, scheduling) could affect scores. Each section must use only one format to avoid confusion during the lab. Which experimental design is most appropriate?