Input to the ALEKS system is always in the form of proper expressions and constructions, never multiple choice. A critical reason for this is to prevent substantial inaccuracies which arise from students' guessing and trying out the different choices.

The general term for the input tools used in ALEKS is the "Answer Editor." This encompasses a variety of actual modes for user input: an Answer Editor for mathematical expressions, an Answer Editor for the numberline, and an Answer Editor for graphing in the Cartesian plane (with x and y coordinate axes). A student beginning to use ALEKS is thoroughly trained in all features of the Answer Editor that are relevant to the subject being studied during the Tutorial (See Sec. 3.8).

In much of what follows, emphasis is on the "Answer Editor for mathematical expressions," as this is the section which involves the greatest degree of interplay between mouse, keyboard, and on-screen buttons and icons.