If when attempting to a launch lesson you get an error message stating the lesson or demonstration is missing, please do the following:

1. Open the Download Lesson Packs window
   1. Mac/Windows: From the Options menu at the top select Download Lesson Packs
   2. iPad: From the menu at the top left select Download Lesson Packs
2. Remove The Essentials
3. Re-download The Essentials
4. Try launching the lesson again.

If that doesn't work, contact at the top of this page.