What Nice Legs!

It had been 4 hard, grueling years of computer science courses for John,  but the end was in sight, with only one more semester before graduation.  However, he realized he still needed one more general science class to  fulfill his graduation requirements. Rushing to register, he found the   only course still available was on "Birds and their habitats". Reluctantly, John signed up.
 
Like many elective courses at the university, the class was large, and generally taught by one of the professor's assistants. As the semester continued, the work load increased, and he found himself spending more and more time studying birds. To make matters worst, the professor offered only one test at the end of the semester to determine each students grade - It was all-or-nothing. Two weeks prior to the final, John began cramming and re-reading the class books and his notes. As he walked in to the exam room, he was confident that he would not only pass but would fly through the test with little effort.
 
As John began the final, he discovered that each question centered around a picture of... a pair of bird legs. He was to identify each bird by its legs, and then answer the corresponding question. He could not believe it - he had studied so hard, and it all came down to his ability to identify birds by their LEGS?
 
He answered best he could, but after struggling with the test for over an hour, John marched down to the front where the professor of the class was standing and slammed the test down into the pile of other exam books.
 
"This is the sorriest class and you are the worst professor on this campus!"
 
As he started out the door the shocked professor yelled back, "What is your name, young man?"
 
John turned, pulled up his pants legs, held his bare leg in the air, and replied, "You're so smart, you figure it out!"