There’s only one thing more exciting than thinking about sign shapes — and that’s reading about sign shapes.

If you don’t believe me, read the rest of this column aloud and take note of nearby reactions.

I’m assuming most of you have a driver’s license (either now or in the past), which means you’ve completed something called a driver’s license test. And this test always includes identifying signs by their shape.

For example, see a sign? Count the number of sides. Pick a starting point and count clockwise back to your starting point (do not count the starting point twice). Five sides? Bam! This means you’re in a school zone.

Before reading any further, study the accompanying graphic. Jot down your guesses before proceeding to see how well you did (Note: no one has ever identified all eight signs — the prize money continues to grow).

1. Stop Sign — located on the near side/right-hand side of the intersection.

2. School Sign — approaching a school indicating that extra care is needed — a school crossing may also be involved as well as reduced speed limits.

3. Speed Limit Sign — The speed limit is displayed and must be in multiples of 5 mph.

4. Not sure about this one — might be installed wrong.

5. Garage Sale Sign — This sign is stapled to an existing wood pole or similar.

6. Yield Sign — This is another example where counting sides are helpful — like the STOP sign, it is located on the near side/right-hand side of the intersection.

7. This is not a YIELD sign

8. Like #3 except with holes

And after a while, road signs become somewhat invisible — the shape tells you what you need to know. You may not even realize you’re using them.

Sign shapes also help autonomous cars identify speed limits, school zones and railroad crossings. As cars become smarter and do more of the things humans should be doing — it was only a matter of time before a car started reading road signs and finding garage sales.

Chet Skwarcan is president of Traffic Engineering, Inc. in Danville. He is an Indiana traffic engineer with more than 30 years of experience solving traffic problems statewide.