How good are your geometric intuition?

Have you ever hung a photo frame on a wall? Can you hang it straight or is it always askew no matter how hard you try? Can you point the center of your plate? Can you draw right angles without using a protractor? When I was in college, me and my friends used to test our abilities to gauge the length of straight lines and angles without using any equipment. This helped us to liven up the otherwise boring engineering drawing classes. If you haven’t had the opportunity to play such games, then here is one to test yourself with.

The eyeballing game works by showing you a series of geometries that need to be adjusted a little bit to make them right. A square highlights the point that needs to be moved or adjusted. Use the mouse to drag the blue square or arrowhead where you feel it is ‘right’. Once you let go of the mouse, the computer evaluates your move, so don’t let up on the mouse button until you are sure. The ‘correct’ geometry is also shown in green, so you can see where you went wrong.


The test consist of 7 challenges and each challenge is presented three times. The scoring is simple: the computer measures the error you made in pixels for lines and in degrees times two for problems involving angles. Your score is the average error you made during the entire test. The lower your average error, the better. At the end of the test you are shown how you fared compared to other players.

I managed to get a score of 3.85 and the results tell me it’s pretty good!


For me, the parallelogram test was the hardest. As you can see from my score card, I was way off in the parallelogram test while making right angles was the easiest.

So what’s your score?

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