Frequently Asked Questions about WWWAssign

STARTING WWWAssign

How do I log on?

To work on your homework assignment, get to your assignment page. Enter the first letter of your first name followed by your last name as your userid. (e.g., the user name for Jun Wang would be jwang, all letters should be in lower case). Your password is last 5 digits of your Social Security Number.

Why Won't it accept my username?

Be sure to enter your Id in all lower case. That is, enter jwang, not JWang.

Also, be sure you have registered your username with the system. This is only required once, before the first assignment is due. To register your username, contact your instructor.

SUBMITTING ASSIGNMENTS WITH WWWAssign

How do I know you got it?

When you click on the Submit button at the end of the assignment, you should get back a page with your graded assignment. If you get that page, then your answers are successfully recorded on disk. No further action is required.

How do I check my grade?

On the WWWAssign Login screen, instead of pressing the Begin button, press the Key button. You will get the graded answer key for the assignment.

I submitted the assignment multiple times. Which one is graded?

The last assignment is graded.

But I messed up on the last submission -- I'd rather have an earlier one graded.

You should send me a note describing just what went wrong and what you want me to do. (Your old submissions are still there --each subsequent submission just appends to your answer file.) I am usually sympathetic and try to be helpful. Note, however, that it is usually easier (and faster!) for you to just redo that part of the assignment than to try to explain what happened and why you want me to change your answers.

So How Do I Check What My Last Submission Is?

On the WWWAssign Login screen, instead of pressing the Begin button, press the Key button. You will get the graded answer key for the assignment. This will reflect your most recent submission.

GRADING ISSUES

How many significant figures do I need to keep?

The default tolerance for the program is 1%, not a specific number of significant figures. As a rough rule of thumb, if you keep at least 4 significant figures throughout all your intermediate calculations, you will usually be ok.

I put 0.13 and the system marked me wrong, claiming the correct answer is 0.133.

The system is correct. Your answer is wrong. The default tolerance is 1%, and 1% of 0.133 is (about) 0.001. That means that answers in the range (about) 0.132 to 0.134 will be accepted. The difference between your answer of 0.13 and the correct answer of 0.133 is over 2%.

But why is the default tolerance so low?

I have two main reasons:

For some problems (especially multi-part calculations), the accumulation of round-off error can lead to significant errors in the results. It is important not to throw away information along the way. Sometimes, such reckless rounding can lead to completely erroneous results.
Physical effects are sometimes subtle or small. The grading system needs to be sufficiently stringent to detect whether or not you have included all of the relevant physics. For example, suppose that the default tolerance were 10% and that you were working on a problem where the inclusion of friction changed the answer by 5%. With a loose 10% tolerance, I wouldn't be able to tell whether or not you had included friction in your calculations.

I Got The Problem Right, But It Marked Me Wrong.

Whenever in doubt, make a printout of the screen and write down the specific things you want me to check. Actual mistakes are pretty rare, however, so check around with other students to see if they are having similar problems.

In any case, rest assured that your grade will never be lowered due to a mistake on my part.