Tesseract Theme Sidebar Compatibility
As of March 2017, the recommend method for sidebar compatibility is to use LifterLMS Labs: Super Sidebars, a free add-on that allows you to add sidebar compatibility to just about any theme in a matter of seconds without having to write any code. See the full tutorial here.
When using the Tesseract theme, sidebars will work as long as you have sidebars displaying in the Tesseract Layout options under the Customizer. If you select a full-width layout, you’ll want to add the following snippet to your functions.php file. This will ensure that LifterLMS Course and Lesson sidebars display regardless of the site-wide layout options defined by the Tesseract theme.
As is, this adds right-side sidebars to courses and lessons. If you comment out line 16 and uncomment line 15, left-side sidebars will be enabled. You could also pass “fullwidth”, as in line 20, this would make the posts fullwidth.