I found interesting the information regarding systematic mistakes in thinking and reasoning, known as buggy algorithms. The chapter states that these mathematical bugs develop when students incorrectly generalize productions when they encounter new problems. The example used in the chapter is that students when working on regrouping tend to subtract the smaller number from larger no matter in which column the numbers are. I think it's important for teachers to keep this in mind and immediately correct the student because students instead of stopping when they don't know what to do, apply their own rules and can make themselves believe that they are doing the work correctly since their computations are producing answers.