The solution to the pattern puzzle:

Here is one way to look at the pattern: It starts at the upper left corner of the grid and moves down, then to the right lower corner and then up towards the right upper corner and so on, until the last tiles are placed in the middle of the grid. It is a spiral. The red circle is followed by a yellow one, a green one, two blue ones, and then another red circle...
Here is something you can try with a friend who has not seen the pattern. Print a blank grid (You will find it on my special page.) Then tell your friend how to draw the pattern without showing it to him or her! Let me know how it worked.
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