A Tenured Professor Lights a Cigar, Cradles a Snifter of Brandy

A tenured professor lights a cigar, cradles a snifter of brandy in his claw-like hand, and reviews his student evaluations from the previous semester. The numbers were unspectacular, but he beamed with pride as he read the comments. For the first time in a long time, no one responded to the "What can the professor do to improve the course?" question with the classic response "not teach it anymore." There were a number of comments, and since he took his craft seriously, he set about summarizing and organizing the comments into the alphabetical list you see here. Take this data and analyze it using the appropriate tool for continuous improvement. Then recommend to the professor the next tool (out of the tools for continuous improvement)that he should use to take the next step in this analysis.
$$\begin{array} { | l | c | } \hline \text { Comment } & \text { Count } \\\hline \text { Can't understand the book } & 2 \\\hline \text { Enjoyed the class } & 5 \\\hline \text { Expect me to remember prerequisites } & 7 \\\hline \text { Need more feedback on homework } & 3 \\\hline \text { Prefer one class night a week } & 7 \\\hline \text { Slow down } & 15 \\\hline \text { Tests too hard } & 9 \\\hline \text { Work more examples } & 14 \\\hline\end{array}$$