In the United States, the credit hour system is used to calculate the academic work done by a student in universities, both at the undergraduate and the graduate levels. Students need to earn a specified number of credit hours in each degree program to be eligible to be awarded the degree. Apart from computing the amount of academic work done by students, credit hours are also used to compute the tuition and fee for students and determine their academic status. For example, at Virginia Tech, the tuition for each credit isUSD 437.25 for in-state undergraduates for the academic year 2015-16. Similarly, there are different fee amounts for each credit at graduate level and out-of-state enrollment. Moreover, full-time enrollment is defined as enrolling for at least 9 credit hours at graduate level and 12 credit hours at the undergraduate level. In order to obtain an undergraduate degree, a student is typically required to earn around 120 credits. In order to earn a graduate degree, the requirements vary starting from 30 to 90 credits depending on the type of degree.
In order to complete an undergraduate degree in four years, one needs to take 15 credits per semester on an average. According to the US Department of Education, to earn 1 credit, a student needs to spend 1-2 hours per week in-class and 2 hours of preparation time out of class. This means that a student who takes 15 credits per semester is required to spend 15-18 hours of time in class and 30 hours of time out of class. This sums up to almost 45-48 hours of academic work each semester. I think this is a very high expectation from students, especially considering the fact that students need to spend time on extra-curricular activities and co-curricular activities in college for which they do not get any credit. And if a student does a part-time job besides attending full-time college, something that a lot of students do, the number of hours which they need to spend on school and work easily add up to around 55-60. This means students have very little personal time in college. In order to meet their job and college requirements, a lot of students neglect their health and social life. This, in turn, leads to heath and psychological issues for them.
The situation gets even worse in graduate school. A lot of graduate students do a 20-hour assistantship besides their full-time graduate level academic work which is 9-12 credit hours per semester. At Virginia Tech, a graduate student on any assistantship is required to take 12 credit hours per semester. Although the in-class hours for graduate students is less than those of undergraduate students, due to the nature of graduate courses, the out-of-class hours per credit are greatly increased. Even if we assume that each credit in the Graduate School at Virginia Tech requires a total of 4 hours of academic work (this is only 1 hour per credit more than the undergraduate credit requirement), this would mean that each graduate student with a 20-hour assistantship needs to spend 68 hours on academic work and assistantship. Needless to say, this is impractical considering this is required of them each week of a semester.
However, this is not to say that students actually spend the same number of hours per week as discussed above to obtain their degrees. Studies have shown that students, especially undergraduates, spend a lot less than 3 hours per week to earn a credit. I myself have earned a graduate level degree at Virginia Tech but do not think I spent 4 hours per credit for all the credits I earned for the degree. But whatever number of hours students actually spend to earn their degrees, in theory, the requirements seem too difficult and taxing.