Heading structure is incorrect on Lessons pages.
It goes from h1 to h3, then h2:
- Sites list begins here (h1)
- Tools list begins here (h1)
- Content begins here (h1)
- Editing tools (h3)
- Main content (h2)
The hierarchy needs to be corrected.
Image from JAWS identifying incorrect header structure in Sakai 12 below (similar issues exist in Sakai 11.4/11.x, per attached images):