Penrose tiles are a kind of tiling that creates shapes various with five fold symmetries. They were invented by Roger Penrose, who is still alive as of this writing in the early 21st century. This is a very rare thing! I cannot think of any other piece of math that is accessible and interesting to people outside of pure math research named after someone not long dead by the time I was born. We learn in school about things named after people like Gauss, Pascal, Laplace, or Euclid. Not someone who might still have office hours. But in this case not only is the inventor alive, but the idea is so simple anyone can play with it at home with some art supplies and trash.
What you will need for this:
Pen or marker
Paper cutout of a pentagon
Ruler or straightedge
Step 1: Trace Pentagon, Draw Pentagram
As shown in the figure, trace the pentagon cutout(see my Golden Triangle Instructable), and then use a ruler to draw in the pentagram on the cardboard as shown.
Step 2: Cross Out the Unused Parts of the Pentagon
I find this to be a useful way to build this up that is easy to remember: cross out the parts of the pentagon you're not going to use as shown in the image. What's left should be a four sided figure.
Step 3: Find Middle Point and Add Connecting Line Segment
Use ruler to connect dots to make the figure shown in the images.
Step 4: Cut Out the Tiles
This tiling is called the "P2" or "kite and dart" tiling. I like it more than the other Penrose Tile systems because it's so simple and the names exactly describe the tiles. I definitely think if you're going to choose just one Penrose tiling to play with this is the one.
Step 5: Trace Lots of Tiles on Cardboard
Trace lots of tiles on cardboard. Note that your lines are all outside the model tile, so if you cut along these lines you end up with a bigger tile, so you'll need to cut inside these, not on them.
Step 6: Paint(optional)
I painted one type of tile red and one blue using acrylic paint. For cereal boxes this is probably not the best way I could have done this, however, since one can just choose cereal brands based on color of packaging, and cut out accordingly to get very bright sharp colors without needing any paint.
Step 7: Cutout, Arrange, Document, Share
There are an infinite number of ways you can lay these out. Searching around on search engines will turn up some amazing examples. Some will be with this type of tile and some won't of course, but this is a very common tiling. Also use examples from online searches to get inspirations for color or pattern to add to the tiles.