Many instructors already use WordPress to run course websites. Now they can also use WordPress to let students securely check their grades online.
That's because Excel is dumb. All the warnings are telling you is that you'll lose formatting--only text can go into a CSV--and that only the active sheet will be saved in the CSV. But all your formatting and multiple sheets will remain in the original Excel file. When you click "Save As," you create a copy of the original in CSV format. Just save the CSV to your desktop and delete it after uploading it.
Sweet. Open the plugin file and look for this...
define('KBGV_WPUSERS', false );
... and set it to true. Once you do that, the plugin will use WP's native authentication system rather than using its own randomly generated passwords.
No. The plugin will notice the new students and generate passwords for them. The dropped students will remain in the passwords database, but they will no longer be able to log in and check their grades (since they won't show up in the gradesheet).
It works like a charm with my versions of Excel and Firefox, but I haven't tested other arrangements. Please let me know what error messages you're getting (if any), what spreadsheet program you're using (and version), what browser you're using (and version), and what platform you use (Windows/Mac/Linux). I don't guarantee that I can fix it, though.
If you have more than 99,999 characters within a single row of your spreadsheet, then everything from the 100,000th character on will get cut off. To fix this, open the plugin file and increase this setting to something higher:
If you have PHP 5.0.4 or higher, set it to 0 to make line lengths infinite.
To protect my legal rear end, I'll say that it is your job to look at the code and decide whether your data will be secure; I make no guarantees. But I do use this software myself and am comfortable doing so. If the MySQL database that holds all your WordPress information is secure, then your gradesheet should be secure.
When students punch in their email address and password, they will see only their own grades on the next screen, not the entire gradebook. It is possible (but not likely) that something could go funny when you import your gradebook, and a student might end up seeing somebody else's grades instead of his own. To rule out this possibility, you will have the opportunity to check the imported gradesheet for errors before it becomes live on your site. (And even if this did happen, the student would probably have no idea whose grades he was looking at anyway.)
The most likely way that data might be insecure would be if a student viewed their grades and then left them up on the screen and walked away. In this case, somebody else might see them. So you may want to post a note on your grade viewing page reminding students to close the browser after checking their grades to help prevent this. (But frankly, it would be your students' fault for not protecting their own data.)
You may ask questions by posting a comment to the KB Gradebook plugin page.