Is it Professor Kenna Griffin or professor Kenna Griffin?
If you chose the first one, you’re correct.
The rule is the same as that regarding short and long titles.
The short title always goes before the name and is capitalized. For example, Professor Kenna Griffin is teaching the course.
A long title (three words or more) always goes after the name and is lowercase. For example, Kenna Griffin, assistant professor of mass communications and director of student publications, is teaching the class.
Note that commas are used to offset long titles, but not short ones.
Also, when working with titles, lowercase modifiers like the word department. For example, The department Chairman Jon Dough said the class will be full.
Remember that you generally avoid courtesy titles in your writing.
If you remember the short/long title rule, it will serve you well in a variety of writing. So, two words or less goes before the name and is capitalized. Three words or more goes after the name and is lowercase.
Now go forth and use words correctly!