1. A method comprising: locating a plurality of occurrences of a knowledge point in a learning material; selecting one or more candidate initial points from the plurality of occurrences of the knowledge point; setting a first candidate initial point of the one or more candidate initial points as a first initial point; creating a first window in the learning material that includes the first initial point, wherein the first window includes a first-window size that corresponds to one or more basic units; creating a second window in the learning material, wherein a start of the second window follows a start of the first window by a first separation size, and wherein the second window includes a second-window size that corresponds to the one or more basic units; calculating a window similarity between first-window content of the first window and second-window content of the second window; in response to the window similarity between the first-window content of the first window and the second-window content of the second window meeting a similarity threshold, generating a first segment with first-segment content that includes at least the first-window content and the second-window content; detecting a position for a first segment border of the first segment that indicates an end of the first segment in which the detecting includes: sliding the first window and the second window through the learning material by a step size to create a first new window and a second new window such that the second-window content of the second window is the same as first new-window content of the first new window; and determining whether a new-window similarity between the first new-window content and second new-window content meet the similarity threshold; calculating a first-segment consistency measurement for the first segment based on a first-segment similarity between the first-segment content in the first segment and the knowledge point; ranking, according to one or more computer-executable expressions, the first segment with respect to one or more of the following: a second segment in the learning material and a third segment in a different learning material, wherein the ranking of the first segment is based on one or more of the following: a quality measurement, a learning material type of the learning material, a length of the first segment, and the first-segment consistency measurement of the first segment; and recommending the first segment to a learner based on the ranking of the first segment.