Using content libraries and randomized content blocks in Open edX
Content libraries are banks of course content that course authors can use to create randomized content blocks, which will pull in a predetermined number of random assets from the library. This is a good way to ensure that tests and quizzes always have different questions for each student or to create unique experiences for each student.
Fill in the appropriate information and click Create.
Note: This is similar to when you're creating a course, some information cannot be changed later, and the Library Code will be part of the library URL, so it must contain no spaces or special characters.
Add your content.
Adding content to a library is a similar process to what you would normally use to add content to a course. With libraries, however, you are limited to 3 types of components: HTML, Problem, & Video. Other than that, the process is the same.
After you've added content, you can edit it.
After you've added content, you can edit it.Content Libraries are very flexible. You can do anything from change components, duplicate, delete, and even import/export entire libraries (more on that below).
Content Libraries are created to be used in Randomized Content blocks. Follow these simple steps to see how they're used.
Enable content libraries in Open edX Studio
Back in your course, navigate to Advanced Settings and add "library_content" to the Advanced Module List.
Don't forget to hit Save Changes!
Navigate back to the course outline, then to the unit you wish to add the content library to.
Add a randomized content block. To do this, click the Advanced Component button, and then select Randomized Content Block.
Select the library you want to add to the block and adjust your parameters.
If your randomized content block has no library attached to it, you will be shown an error message. Click Select a Library or Edit to set the library you would like to associate with the block. 
Make sure you click Save.
In this example, for this particular unit, students will be shown five random questions from Example Library 1.