17. The system according to claim 11 , further comprising a resource file database hosted on one or more server computers comprising non-transitory machine-readable storage media, the resource file database configured to store one or more records of one or more resources respectively, each respective resource comprising text having one or more words, and each respective record containing the resource difficulty score of the respective resource.
18. The system according to claim 17 , wherein the at least one processor is further configured to determine the resource difficulty score based upon one or more attributes of the text of the resource, and store the resource difficulty score in the record of the resource.