Listening to A Class Lecture

I am a Sign Language Facilitator for K-12.  I was told that Kahn Academy had classroom content that one could listen to so as to practice interpreting class content. Also researching the vocabulary used in various grade levels and subjects so as to interpret them correctly. 

I have not been able to locate any courses.  Currently I am working with an 8th grader.  I selected 8th grade coursework, however; when I click on the courses, I get an "OOPS" screen. 

Can someone please let me know what I should do differently.

Thank you, 

Catherine 'Cat' Donati