Browser cache is the method computers use to "remember" or store web pages for fast access later. While typically a good thing, sometimes this process can cause intermittent problems accessing the lessons and needs to be overridden.
Many cache issues can be solved by reloading the page and bypassing the cache. To do this, open the page, then press and hold down the Ctrl key (Cmd ⌘ on Mac) and tap the F5 button.
If this doesn't solve your problem, read on for instructions on how to completely clear your browser's cache...
Clear the Browser Cache Manually
In Google Chrome
With Chrome selected press Ctrl + Shift + Del or click the ⋮ menu button and locate More tools > Clear browsing data...
Make sure you select the beginning of time as the time range and only select Cached images and files check box, then click the Clear Browsing Data button.
In Mozilla Firefox
With Firefox selected, press Ctrl + Shift + Del or select History > Clear Recent History... from the menu bar. If the menu bar isn't visible, tap the Alt key to reveal it.
Make sure to select Everything as the time range and only select the Cache check box, then click Clear Now.
In Microsoft Edge
First, click the · · · menu button in the top right corner, then click on Settings. Next, under the Clear browsing data section, click on Choose what to clear.
Finally, make sure that only the Cached data and files box is checked and then click on the Clear button.