The Case of the Missing Fractals

I happened upon this 2014 lesson called The Case of the Missing Fractals when I was looking for something else, and wow what a gem! I am definitely going to share it with my students next year. One year I was lucky enough to start talking about fractals in my Pre-Calculus Honors class. I posed the question, what fractal will have 0 area as the number of iterations goes to infinity? And then,  and what fractal will have infinite perimeter as the number of iterations goes to infinity? This Ted-Ed lesson explains exactly that in a very cute way. Kids will be hooked as gumshoe "Manny Brot" answers riddles about fractals.

The "Dig Deeper" section in the lesson has terrific links, including another Ted-Ed lesson about Flatland shown below:

There are so many great lessons on ed.ted.com, and you can customize them as you see fit. 

What great Ted-Ed lessons have you found and used in your math classroom?