When Alan Alda was 11-years-old he wondered, 'what is a flame?' He asked his teacher and the answer wasn't very satisfying, Alda told Ira in our New York studios last March. Sixty years later, Alda was still looking for a good answer so he launched a "flame challenge", a contest asking scientists to explain how a flame works in a way that 11-year-olds can understand. The votes have been tallied. Alan Alda is back this week to give us the results. [2:51]