Locks have been around for thousands of years. Probably as long as there have been valuables that people wanted to protect, locks — in some form — have been there to keep things secure.

You probably encounter all sorts of locks every day. From combination locks on school lockers to deadbolt locks on front doors, locks are all around us.

Today there are many different kinds of locks. Some are very simple locks that open with a key or a combination of numbers. Others are extremely complicated locks that open with fingerprints or special electronic keycards. Today’s locks feature many different types of mechanical and technological systems to increase security.

To get a basic understanding of how locks work, let’s take a look at two common types of locks: combination locks and pin-and-tumbler locks. These common locks are the ones you’re most likely to see on a day-to-day basis.

Combination locks can be found in all sorts of places. From gym lockers to shed doors to secret diaries, combination locks allow their contents to be accessed only by those who know the secret combination of numbers that will open the lock.

A typical combination padlock, for example, contains a wheel pack. The wheel pack contains one wheel for each number in the combination. Each wheel in the wheel pack has a small tab — called a wheel fly — on each of its sides.

As you turn the combination dial, a spindle that extends through the wheel pack turns a drive cam. As the drive cam turns, an attached drive pin makes contact with the wheel fly on the nearest wheel.

As you continue to dial in the correct combination, the wheel fly on each subsequent wheel makes contact until all the wheels are spinning. When you get to the last digit of the combination, all wheels will be lined up perfectly.

Notches cut into each wheel will also be aligned. These notches form a gap that will allow the lock to release and open.

Pin-and-tumbler locks are different, because they require a key to unlock them. Basic pin-and-tumbler locks have several spring-loaded pins inside a series of small cylinders.

When the right key slides into a pin-and-tumbler lock, the pointed teeth and notches on the blade of the key allow the spring-loaded pins to move up and down until they line up with a track called the shear line. When the pins align with the shear line, the cylinder can turn and the lock will open.

If you don’t have the right key, one or more of the pins will remain in the way of the shear line. This will prevent the cylinder from turning and the lock will remain closed.

62 Join the Discussion

1 Star2 Stars3 Stars4 Stars5 Stars  (29 votes, avg. 3.62 out of 5)
    • Thank you! We are already having a nice day today, Nour! Do you know why? It’s because we are reading all the AWESOME comments our Wonder Friends (like you) have left for us! 87 locks is a LOT of locks! Thank you for sharing that you counted all of yours! :-)

  1. Now I know how the keys are made! That’s actually really interesting how they are made. I used to think that the keys took longer to make, but I guess not.

    Have you thought about making that blog I asked for?

    • We sure have, Moises! We left you a reply to your comment where you suggested that there be a Wonder about the Illuminati and other secret societies. Did you read it yet? We hope so! We really listen to each and every suggestion our Wonder Friends give us about what they think future Wonders of the Day should be! It takes a good bit of time, research and extra WONDERing to turn a great idea from a Wonder Friend into a Wonder of the Day® that all Wonder Friends can enjoy! We appreciate your suggestion very much! :-)

  2. This video was really cool. Now I know if i get locked out, I will know what to do. I love your wonders. They teach me something every time I watch them. Thanks You For Another WONDER, WONDEROPOLIS!

    • Your comment just made our day, Dominque! Thank you for the nice things you said. We like hearing that you learned some new things about locks today! We’re also so happy to hear that you love visiting Wonderopolis! :-)

  3. Locks are something on a door, on a car, or on a garage. I learned that there are two types of locks, key locks and combination. One time, my dad told me when he was a kid, someone stole his game. Sometimes I think someone is in my house. I make sure I lock the door and the gate is closed and locked. Stay safe, kids! :)

    • Thanks so much for sharing your personal connection to today’s Wonder about locks, Eric! We’re sure glad you learned some awesome new things about them today! :-)

  4. My sister has an electric lock on her garage. The Sheriffs put a lock on our garage so we cannot shut it. I love WONDERs.

    • Electric locks, like the one on your sister’s garage, sure do make life easier sometimes, Nolan! Thank you for visiting Wonderopolis today and for sharing your personal connection to today’s WONDER! :-)

  5. The video AWESOME. It was cool to see how locks work. AWESOME. I LOVE Wonderopolis! Wonderopalis is AWESOME. You know that I don’t have those kind of locks. I have the kind that you can twist the locks. It’s my birthday.

    • Happy birthday to you, Hailey! We hope you have a WONDERful day today! Thanks so much for sharing about another type of lock! We bet there are LOTS of Wonder Friends who have a “twist” kind of lock, too! :-)

  6. Locks are kind of confusing to us, but we have mastered our grade 5 combination locks. We’ve always wondered how they work! Wonder who “invented” the first lock??
    Confusing, but amusing!
    We like the ones on animals, and… hockey! Could you do one on hockey soon?

  7. We think tomorrow’s wonder of the day might be about polar bears or ground hogs or penguins or bears.

    We check the website everyday, so we will look forward to seeing tomorrow’s!

    • It makes us SUPER happy to hear that you visit Wonderopolis every day, Room 20 5th grade Mapleshade School! We think it’s AWESOME that you like to WONDER just like we do! Thank you for guessing what tomorrow’s Wonder might be…we can’t wait to see if you are right! :-)

    • We think learning about locks was pretty interesting, too, SINYOR PICONTE! Thanks for leaving us another comment today! :-)

  8. Sick from school today, but feeling better!
    That is an awesome fact!
    Keep healthy…get your flu vaccinations!
    You know, you should do a wonder on how flu vaccinations work on your body!
    See you tomorrow!
    mak – makayla

    • We’re super sorry you’re sick today, Mak! We’re glad you’re feeling a little better, though, and REALLY happy that you visited Wonderopolis today and learned some new things! Did you know there is already a Wonder of the Day® about shots? The video even talks about kids getting their flu shots! It’s Wonder of the Day® #395 – Why Can’t All Medicine Be Swallowed? http://wonderopolis.org/wonder/why-cant-all-medicine-be-swallowed/. :-)

    • What an awesome comment, Gareth! Thank you for letting us know that you’re a new Wonder Friend! We’re really happy that you like hanging out in Wonderopolis with us and learning new things! :-)

    • We were WONDERing if any Wonder Friends would ask that question today, John, Jack and Chris! We’re not sure how to pick locks, but there are special professionals called “locksmiths” who help people when they get locked out of their cars or houses. Let’s leave the lock-picking to them! :-)

  9. There are 2 main-types of locks called keylocks/combination locks. We use locks so strangers can’t get in your home/house.

    • You’re absolutely right, Josh! Way to go! Thank you for leaving us this great comment today to let us know some of the awesome things you learned about locks! :-)

    • A Wonder about red tides would be GREAT, Cate! Thank you for suggesting that idea for a future Wonder of the Day®! :-)

    • That’s an awesome, enthusiastic rhyme to go with today’s Wonder of the Day®, Rebecca! We think you and all of our Wonder Friends ROCK, too! :-)

    • Hello, Gemi! We liked learning about locks today, and we’re glad you did, too! Thank you for being a friend of Wonderopolis! :-)

  10. Dear Wonderopolis,
    Hello! I am in team CAISSE’s 5th grade reading class. Today’s WONDER made me WONDER if there is a key in the world that can open any lock or a combination that can unlock any lock. Wouldn’t that be radical! I am still thinking you should have a WONDER of the day about wonders of the day! Remember, if you do GIVE SARAH CREDIT FOR THE IDEA!!!!!!!!!
    From the awesomest, most radical girl in the universe, SARAH

    • We think that really WOULD be radical if there was either a key or a combination that could unlock any lock in the world, Sarah! You’re super smart to think of that! Thanks for being such a fun and energetic Wonder Friend! :-)

    • We got your lazy day comment, Nour…thanks so much for sending it! We sent you a reply that had a link to Wonder of the Day® #125 about hiccups, and also had a link to Wonder of the Day® #1 about flamingos! Did you get a chance to visit those awesome Wonders yet? :-)

  11. Yes I did, and thanks for the effort you put to that reply, but I don’t mean the comment. I meant I emailed you a blue list of stuff to make my lazy day perfect. Did you get my email or not?

    • Yes, we got your email, Nour, and we think it is…AWESOME! Thanks so much for sharing it with us! The “Things to do on a lazy day” side sounds like a lot of relaxing fun! We especially like “Stay up until 12:59″ and “Read 2 interesting books!” We like everything you listed on the “Things not to do on a lazy day” side, too! “Do stuff for other people” and “Be creative” ROCK! :-)

    • Thanks for leaving us this comment, Jo Jo/Saydi! We’re glad you like to hang out in Wonderopolis and learn new things! :-)

  12. We read this wonder today however the sound on the video did not work. We could hear the sound of the key being cut but no sound of the man’s voice. Thanks.

    • Hey there, Ms. J’s Grade 3/4 Class! Thanks for visiting Wonderopolis today… we’re sorry to hear that you were having trouble hearing the man’s voice in the video. Perhaps you will have better luck by visiting the video on vimeo: http://vimeo.com/15692380# :)

      We hope you enjoyed WONDERing with us! Have a terrific Thursday! :)

    • We’re so thrilled that you enjoyed the WONDER, Alyssa! We think you’re pretty awesome too! Groundhogs are fuzzy with fur! Thanks for WONDERing with us! :)

  13. I liked this story because it helped me understand the way lockers work, so now when I get older I can work as a locksmith. Because I know how lockers work and I like reading Wonderopolis, I’m going to read more stories.

Leave a Reply

Your email address will not be published. Required fields are marked *

You may use these HTML tags and attributes: <a href="" title=""> <abbr title=""> <acronym title=""> <b> <blockquote cite=""> <cite> <code> <del datetime=""> <em> <i> <q cite=""> <strike> <strong>


  • Wonderopolis on Facebook
  • Wonderopolis on Pinterest
  • Print

Have you ever wondered…

  • How do locks work?
  • Are all locks the same?
  • How do keyed locks differ from combination locks?

Wonder Gallery

key_shutterstock_3325571dreamstime_xl_974187 (Custom)dreamstime_xl_30766231 (Custom)dreamstime_xl_7616421 (Custom)Vimeo Video

Try It Out

We hope you enjoyed unlocking the WONDER of learning about locks today! Keep the learning going by finding a friend or family member to help you check out one or more of the following fun activities:

  • Ready to get some hands-on experience with locks and keys? Ask a friend or family member to let you borrow their keys for a little while. Compare the keys. How are they similar? How are they different? Can you see how the bumps and ridges are different on all the keys? How many keys do they have? What sorts of locks do they open? There are probably car keys and house keys. What other types do they carry? Pick out a couple of the keys and give them a try. Do they unlock easily? Does one key work in more than one lock? Or does each lock require its own special key?
  • Look around your house and find several types of locks. There are probably locks on external doors. There may even be locks on some internal doors. Do you have any drawers or cabinets that lock? Do you have any padlocks or combination locks around your house? What about at school? How do these locks differ from the locks that use keys? Are you surprised by how many locks there are around you? After a while, we tend to take them for granted, since we see and interact with them all the time. If you pay attention, though, you might be surprised by how many locks you come across in a normal day.
  • Up for a challenge? Get some practice for your future career as a spy. Using a few simple items, learn how to copy and clone a key! You’ll need help from an adult for this activity. Have fun learning how to make a copy of a key. When you’re finished, test it out. Did it work? Could you have a future as a spy? Maybe!

Still Wondering

Check out Thinkfinity partner The Electric Company to unlock the power of words through multimedia literacy experiences designed to teach reading concepts through fun and engaging videos, games and activities.


Test Your Knowledge

Wonder What’s Next?

We hope tommorrow’s Wonder of the Day brings back some WONDERful memories!

Upload a Photo or Paste the URL of a YouTube or SchoolTube Video.