Less Is More: Students Skim Lengthy Online Textbooks

Abstract—Computer science textbooks with lengthy text
explanations of concepts are often considered thorough and
rigorous, so lengthy textbooks (and class notes) are commonplace.
Some, however, suggest text should be concise because people tend
to skim lengthy text. This paper takes advantage of modern digital
textbooks that measure reading time to examine reading rates for
various text passage lengths. For a widely-used CS textbook
written in a non-concise style, students read shorter passages (200
words or less) at about 200 words per minute, which is a typical
rate. But for longer passages (600+ words), the rate increased to
about 800 words per minute, suggesting skimming rather than
reading. For another widely-used CS textbook, from the same
publisher but written in a concise style with text passage sizes kept
below 250 words, students spent more time (around 200 words per

minute) reading the text passages, and their time spent was well-
correlated with text length, suggesting students were carefully

reading rather than skimming. Across three digital textbooks, the
more interactive elements (e.g., integrated questions) that were
included, the more time students spent reading the text between
those activities. The conclusion is that to best educate students,
authors of CS content should take the extra time needed to explain
concepts more concisely – a case of “less is more” – and
incorporate many active learning opportunities.


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