Where is Fibonacci?
Have students watch Vi Hart Doodling in Math Part 1, Vi Hart Doodling in Math Part 2, and Vi Hart Doodling in Math Part 3 . Knowing your students, decide what you feel would be best; whether to project the video and watch it together whether to have students what it independently. I have done it both ways and see benefits to both.
Personally, I like to leave the kids watching and guessing and only stop the video and allow students to respond rather than trying to have too much of a teacher-guided discussion during this time.