Todays graph indicates that searches for two seemingly unrelated words, "cliff" and "spark", follow the same pattern. Now, why is this the case? I believe that the answer is related to the school schedule in the United States. As the graph clearly indicates, searches for "cliff" and "spark" are at their lowest levels during the summer and also decrease significantly around Thanksgiving and Christmas. The declines in the searches for the terms coincide with the time periods that students have time off and are unlikely to do work.
Cliffsnotes and Sparknotes are popular literature and study guides that allow students to write book reports without actually reading any books. It is the searches for these literature guides that is driving the pattern seen in the graph. The increase in the spread between "cliff" and "spark" suggests that Sparknotes have increased in popularity relative to Cliffsnotes. The high popularity of both of these terms in certain areas might suggest that students in those locations are more prone to taking shortcuts when writing papers...
(Sparknotes was acquired by Barnes & Noble in 2001 - J)
A live view of this trend is available here.