1. A computer-implemented method of designing an assessment, the method comprising: receiving subject matter information related to one or more subject matters of an assessment; receiving requirements information related to one or more requirements for an assessment; storing the subject matter information and the requirements information in a computer-readable database; generating one or more trifles using a processing system, wherein each trifle is based on one or more of the subject matter information and the requirements information; wherein a trifle provides a reference to a source of the subject matter information or the requirement information on which the trifle is based for subsequent access; storing the trifles in the computer-readable database; generating one or more task models using the processing system, wherein each task model is based on at least one trifle identified via a computer-implemented keyword search; wherein each task model comprises: an identification of an audience for the task model; a format for communicating a task to a student for the task model; a task feature description for the task model; an outcome feature description for the task model; and a task family feature description; storing the task models in the computer-readable database; generating one or more student models using the processing system, wherein each student model is based on at least one trifle, and wherein generating a student model comprises specifying statistical relationships between multiple variables in the student model; storing the student models in the computer-readable database; generating one or more evidence models using the processing system, wherein each evidence model is based on at least one trifle; storing the evidence models in the computer-readable database; generating one or more tasks using the processing system, wherein each task is based on one or more of the task models; and generating and outputting an assessment using the processing system, wherein each assessment comprises one or more tasks, an evidence model corresponding to each task, and one or more student models; wherein a number of tasks of a first kind to be included in the assessment for a particular student is determined based on a student model associated with the particular student, a task model, and an evidence model.