Since you must structure your time differently in an online course than in a traditional classroom-centered course, it may help to think about your time commitment.  This is especially true in a summer course, when you might not even be on campus, and when there may be many other things like jobs or vacationing competing for your attention.

By "the book" (literally: this guideline is in the Lehigh rules and regulations!), the guideline is that in a normal academic semester on campus undergraduate students should expect to put in, on average, 2-3 hours work outside class time for each 1 hour (credit) of class time.  That's 3-4 hours per week total for each credit hour.

In ballpark figure terms, here's the nitty-gritty:

• For a 3-credit class that means 9-12 hours total per week (3 in class, 6-9 outside) for a total of 126-168 hours in a 14-week semester.  A student taking a normal load of 5 3-credit courses would have a 45-60-hour work week.
  

• For a 4-credit class that means 12-16 hours total per week (4 in class, 8-12 outside) for a total of 168-224 hours in a 14-week semester.  A student taking a normal load of 4 4-credit courses would have a 48-64-hour work week.

• By the same proportion, a student taking a 3-credit course in a 6-week summer semester should put in 21-28 hours per week.  And in the summer a maximum course load usually is 2 courses, so that the student has a work week of 42-56 hours.  The expectation is that one must work harder for the same credit in the shorter time frame.
  

• By the same proportion, a student taking a 4-credit course in a 6-week summer semester should put in 28-37 hours per week.  And in the summer a maximum course load usually is 2 courses, so that the student has a work week of 56-74 hours.  The expectation is that one must work harder for the same credit in a shorter time frame.

Now, in reality, no one expects THAT much work.  Probably few teachers are even capable of that kind of commitment.  It's obvious that the university kind of winks at the notion that summer courses are exactly equivalent to academic year courses.

But the fact remains that the severely compressed course rhythm is quite different from the academic year, that students must be prepared to do a substantial amount of work in a narrower time frame that probably has more duties and distractions in it.

The expectation in this course will be that you spend on average about 15 hours per week.