1.39 Teachers use examinations to measure students’

knowledge about their subject. Explain how

“a lack of variability in the students’ scores might indicate that the exam was not a very effective measuring device.” Thoughts to consider: What would it mean if all students attained a score of 100% on an exam? What would it mean if all attained a 0%? What would it mean if the grades ranged from 40% to 95%?