- Reload the page. For your security, the link to each video or document expires after a few hours, and reloading gets a fresh one.
- Check your connection. Large videos need a steady connection; pausing for a moment lets the video buffer.
- Try another browser (an up-to-date Chrome, Edge, Firefox or Safari).
- PDF not showing? Some phones cannot show PDFs inside a page; choose Open the PDF in a new tab.
Still stuck? Report the problem and tell us which lesson and which device you use.