1. Recognize the Altair 8800?

You know you’re an engineer if you know all of the details of the Altair 8800 – the year it appeared on the cover of Popular Electronics, the city that was its home base, the CPU it was based on, the first programming language for the machine, the name of the software wiz who dropped out of Harvard to write for it, and the name of the classic movie where it appears on a shelf.

2. The Second Law of Thermodynamics

You know the second law of thermodynamics but not your shirt size.

3. The Hero of the Apollo 13 Mission

You know you’re an engineer if you thought the real hero of Apollo 13 was the mission control crew, not Tom Hanks or Kevin Bacon.

4. The Erector Set You Keep in Storage

You know you’re an engineer if you still have your original Erector Set in its little red metal suitcase (even if some parts are missing).

5. Baggage Handling Equipment

You know you’re an engineer if you find yourself at the airport on your vacation studying the baggage handling equipment.

6. Great Ideas on a Napkin

You know you’re an engineer if you always have to explain things by drawing it out on paper or a napkin or any other surface available.

7. Miter Saw Blades

You know you’re an engineer if you try to explain to your friend who is working on a home-improvement project that he won't wear out his miter saw blades as fast if he slows down the feed-rate, thus decreasing his chip load, and improving tool life.

8. No Marching on the Bridge

You know you’re an engineer if you can explain why soldiers have to break stride while marching across a bridge.

9. What the Heck is RPN?

You know you’re an engineer if you have ever owned a calculator with no equal key and you know what RPN stands for.

10. Watch the Geosynchronous Satellites

You know you’re an engineer if you’re outside during a camping night, and while everyone is looking at the moon, you’re trying to locate a geosynchronous satellite.

11. What Is Geosynchronous Satellite Function?

You know you’re an engineer if you know what the geosynchronous satellite function is. Or, if you don’t know what geosynchronous satellite function is, you’re breaking away from this page to find out what it is.

12. How Many Half-Broken Objects Do You Own?

You know you’re an engineer if you have half-broken objects in your house that you refuse to throw away because you’re hoping that you can someday find the time to fix them.

13. Clicking Your Circuit Breakers

You know you’re an engineer if you recognize the importance of exercising your circuit breakers--and you do it on the day the time changes because the clocks will be messed up anyway.

14. Adding Oil to Boiling Spaghetti

You know you’re an engineer if you explain how surface tension works when your 10-year-old asks why you are adding oil to boiling spaghetti.

15. Vector Calculus

You know you’re an engineer if you know vector calculus but you can't remember how to do long division.

16. Is Calculus Even Math?

You know you’re an engineer if you know calculus isn’t a high level math.

17. What’s 42?

You know you’re an engineer if you know the significance of the number "42." Hint: Not the movie about Jackie Robinson.

18. That’s a Pretty Smart Dog

You know you’re an engineer if you have a pet named after a scientist. “Here’s a treat, Tesla.”

19. Got Any Test Equipment?

You know you’re an engineer if you still have perfectly good test equipment in your garage that you haven’t used since the 1980s.