### Beware of Notation

I gave an exam today. Much the same as what you've come to expect from my students and my exams -- even after the whole pigeonhole principle quiz disaster, some of them still don't know what the pigeonhole principle is. As a whole, I think that the grades gave a pretty fair indication of the students' understanding of the material. A good exam overall.

Many students were done in by notation. I sort of knew that this would be a problem and put at the top of the exam the following:

We had used this notation in class. I made a big fuss about it. We practiced with several examples and wrote the recurrence relation that defines the Fibonacci sequence. The notation came up in the homework. I made another fuss when we went over the homework.

Unfortunately for my students, they seem unable to tell the difference between

Many students were done in by notation. I sort of knew that this would be a problem and put at the top of the exam the following:

**Reminder:**The notation*F*stands for "the_{n}*n*^{th}Fibonacci number."We had used this notation in class. I made a big fuss about it. We practiced with several examples and wrote the recurrence relation that defines the Fibonacci sequence. The notation came up in the homework. I made another fuss when we went over the homework.

Unfortunately for my students, they seem unable to tell the difference between

*F*,_{n+1}*F*+1, F times (n+1) , and_{n}*n*+1. (If it isn't showing up well in HTML, these are: F_{n+1}, F_n +1, F \cdot (n+1), and n+1.)