"Is this really a proof?" is the exact question e-mailed to me today from an undergraduate mathematics student whom I know as a highly competent student. The one sentence question was accompanied with the following demo:

![enter image description here][1]

I am looking for a down-to-earth, non-authoritative answer who one may give to such a student. What would be your answer if you were faced with such a question?  


**Update after closure**. Reading the comments you may realized that most of them answer the original title of the post: "Is this really a proof?" Of course, the answer to such a question is as clear as the daylight for MO users. And, such a question should be closed asap. But, the actual question was (is) in the body of the post, and it was (is) what your **constructive** answer would be **to such a student** if you were faced with such a question. Now, with the change of the title, the actual question is much more clearer, and I hope, worthy of MO attention.  

   
  [1]: https://i.sstatic.net/aN3Uy.gif