In my experience, critical thinking is understood and practiced (or not) differently among different ages of students (my classrooms are typically a mixture of older, returning students and younger, early twentysomething students). However, the differences are difficult to predict, and defy conventional stereotypes. Older students are no more or less likely to be skilled in this than the younger ones. I'm convinced that the students' previous educational experiences are the most important variable. Often, it is quite difficult for me to know how well-versed a student may be in critical thinking until the work starts coming in. What are some sound ways of measuring proficiency in this area early in the course?