12. The non-transitory computer-readable storage medium of claim 10 , the computer program instructions further comprising instructions for: serving the job recall material to the user; and storing a response to the job recall material received from the user as a job recall activity completed by the user.
10. A non-transitory computer-readable storage medium storing executable computer program instructions for correlating job recall materials to educational courses, the computer program instructions comprising instructions for: extracting learning units, by an automated learning units extraction system of an online education platform, from content stored on a platform content catalog database of the online education platform, the extracting comprising: performing text extraction on the content to extract sequences of glyphs; mapping the extracted sequences of glyphs and embedded fonts into character strings in a Unicode format; generating multilayered markup language documents from the character strings by aggregating content layers onto the character strings; identifying, from the multilayered markup language documents, content media types of the content comprising primary sources and secondary sources, the primary sources comprising one or more of a summary, a syllabus, and a textbook, the secondary sources comprising one or more of related content, user-generated content, Q&A, and testing materials, and sorting the content media types according to reliability of the content media types, wherein reliability of the primary sources is higher than reliability of secondary sources; receiving at the online education platform, a job recall material uploaded to the online education platform; mapping, by the online education platform, the job recall material to at least one of the learning units; and responsive to a user of the online education platform completing the at least one of the learning units to which the job recall material is mapped, recommending the job recall material to the user.