Oh, this seems to require a login. And $25. So let me just give you some general suggestions: '''Check for a possible Flash activation requirement:''' If the quiz/course uses the Flash plugin, Firefox will display an icon toward the left end of the address bar to activate Flash on the site. More info in this article: [[Why do I have to click to activate plugins?]] '''Double-check content blockers:''' Firefox's Tracking Protection feature and extensions that counter ads and tracking may break websites that weren't built to operate normally without the blocked components. Do you see a shield icon toward the left end of the address bar, near the lock icon? More info on managing the Tracking Protection feature in this article: [[Tracking Protection]]. Extensions such as Adblock Plus, Blur, Disconnect, Ghostery, NoScript, Privacy Badger, uBlock Origin or uMatrix should provide toolbar buttons to manage blocked content in a page. There may or may not be a number on the icon indicating the number of blocked items; you may need to click the button to see what's going on and test whether you need to make an exception for this site. '''Cache and Cookies:''' When you have a problem with one particular site, a good "first thing to try" is clearing your Firefox cache and deleting your saved cookies for the site. (1) Clear Firefox's Cache See: [[How to clear the Firefox cache]] If you have a large hard drive, this might take a few minutes. (2) Remove the site's cookies (save any pending work first). While viewing a page on the site, try either: * right-click (on Mac Ctrl+click) a blank area of the page and choose View Page Info > Security > "View Cookies" * (menu bar) Tools > Page Info > Security > "View Cookies" * click the padlock or "i" icon in the address bar, then the ">" button, then More Information, and finally the "View Cookies" button In the dialog that opens, the current site should be pre-filled in the search box at the top of the dialog so you can remove that site's cookies individually. Then try reloading the page. Does that help? '''Testing in Firefox's Safe Mode:''' In its Safe Mode, Firefox temporarily deactivates extensions, hardware acceleration, and some other advanced features to help you assess whether these are causing the problem. ''If Firefox is not running:'' Hold down the Shift key when starting Firefox. (On Mac, hold down the option/alt key instead of the Shift key.) ''If Firefox is running:'' You can restart Firefox in Safe Mode using either: * "3-bar" menu button > "?" Help > Restart with Add-ons Disabled * (menu bar) Help menu > Restart with Add-ons Disabled and OK the restart. ''Both scenarios:'' A small dialog should appear. Click "Start in Safe Mode" (''not'' Refresh). Any improvement?