2 + 2 = 5. Oops! Not quite… now where did I put that eraser?

Mistakes happen all the time. And that’s OK. Everyone makes mistakes. The important thing is to learn from them… and erase them as soon as possible once you spot them!

Have you ever stopped to think about exactly how that little pink piece of rubber at the end of your pencil is able to erase what you’ve written? Is it magic? Nope! There’s a perfectly logical, scientific answer.

Before we get to how erasers work, though, let’s learn a bit about what exactly is on the paper that you’re erasing. Although we call the black stuff in pencils “lead,” it’s not the real metal known as lead.

It’s actually a mineral called “graphite,” which is made up of carbon. When you write with a pencil, graphite particles from the pencil rub off and stick to the fibers of the paper you’re writing on.

While pencils are filled with graphite, erasers are made mostly of rubber, although plastic and vinyl are sometimes used. The rubber is usually combined with sulfur to make it last longer.

A softener, such as vegetable oil, is also usually added to make the eraser more flexible. Finally, abrasives, like pumice or quartzite, are added, along with dye to give the eraser a particular color.

When you rub an eraser across a pencil mark, the abrasives in the eraser gently scratch the surface fibers of the paper to loosen the graphite particles. The softeners in the eraser help to prevent the paper from tearing. The sticky rubber in the eraser grabs and holds on to the graphite particles.

Erasers work because of friction. Try rubbing your hands together right now. Do you feel them getting warmer the longer you rub? The warmth you feel is the heat generated by the force of friction created by the rough surfaces of your hands rubbing together.

As the abrasives in your eraser are rubbed against paper, friction produces heat, which helps the rubber become sticky enough to hold onto the graphite particles. As the rubber grabs the graphite particles, small pieces of combined rubber and graphite get left behind. That’s the “stuff” you brush off of your paper when you’re finished erasing.

An English engineer named Edward Naime invented the eraser in 1770. Up until that time, people usually used rolled-up pieces of white bread to erase pencil marks.

Legend has it that Naime accidentally picked up a piece of rubber instead of bread and discovered that it would “rub” out pencil marks. That’s where the name “rubber” comes from.


43 Join the Discussion

1 Star2 Stars3 Stars4 Stars5 Stars  (29 votes, avg. 4.66 out of 5)
  1. I am new to Wonderopolis and I love it! I intend to use it to encourage curiosity in my students. I hope to feature a wonder topic at least once a week for my students to write and respond to. I would love to share the Wonderopolis erasers with my 70 fifth graders to let them know it is ok to make mistakes and make changes.

    • Welcome to Wonderopolis, Karyn! Thanks so much for commenting today about how you will engage your students with Wonderopolis! What a GREAT thought…we can learn a lot and grow from our mistakes! :-)

  2. I am excited to start my year off using Wonderopolis in my classroom with my morning warm up. It is fun to have the wonder up and have the students come into the room unpack their book bags, hand in their HW and begin thinking and talking about the wonder of the day. If we have time we watch the video and then later in the day we will come back to the wonder and read the article as a class to see if we were correct about our guesses. Then we have had a WONDERful day.

    • Hi, Maria! Using each day’s Wonder as a morning warm up is an AWESOME idea! Thanks so much for sharing this with everyone! :-)

  3. Wonderopolis is the BEST site ever!! I am at an elementary school that is an IB school – inquiry and critical thinking is what it’s all about. So when I found Wonderopolis I thought I had struck gold! It is perfect for the end of the school day. The students are so excited to share what they already know, we then watch the video, and then talk about the “did you know” info and the word bank. They often go home with a challenge to bring back more info for the next day’s morning meeting. So instead of being just ready to get out & go home, they leave excited & ready to “wonder” & discover more!! THANK YOU!

    • Sending your students home with the desire to WONDER and discover more is AMAZING, Debbie! Thanks so much for sharing your end-of-day strategies for utilizing Wonderopolis in your classroom! :-)

  4. Wonderopolis works WONDERFUL for my homeroom block to engage interest and combat behavioral issues and the tendency to have to be yak, yak, yaking at the kids to find something to do. With Wonderopolis, they are engaged and we are able to have a discussion afterwards.
    Thanks so much! :)

  5. This is my first time visiting Wonderopolis and I love it! I am a 4th grade teacher and would use it in my homeroom time. Later on when we do personal journals, I will have them respond to what they saw and read! Thanks for the chance to win some awesome erasers!

    • We’re glad you stopped by today, Sandyh50! We love to hear about students journaling with Wonder…thanks for your comment! :-)

  6. Will be featuring clips once a week on the morning announcements. Already started a sort of interactive bulletin board (CREDITING THE SOURCE, of course) with some questions and then flip the cover over to find a summarized answer. Hoping to start a sort of Wonder Investigation Team where kids answer questions submitted by other kids. As the librarian inquiry and curiousity are my FAVORITE! (PS For other teachers, I just finished a book called A Place for Wonder: Reading and Writing Non-Fiction in the Primary Grades and it is so good. No, I’m not associated with the author and yes, it is easily tweakable for older kids!)

    • Hi, Angie! So glad to have a librarian commenting today! Thank you for sharing your interactive bulletin board idea with everyone…sounds like WONDERful things are in store for the students at your school this year!

  7. This summer I had the opportunity to explore Wonderopolis – it is so engaging and full of visuals. This is perfect for my ELL population!
    I would like to invite my students and their family/parents to Wonderopolis after-school sessions. I would faciliatate navigation through the website, have the family choose one activity to explore and create a project at home. Students will share during “show and tell” sessions in class.

    • Thanks for commenting today, Marie! We are so happy to hear that you have been exploring Wonderopolis! Your idea is a such a creative way to engage English Language Learners AND their families…TOGETHER! Thank you so much for sharing! :-)

  8. My district, Wilson North Carolina, has just started using Thinkfinity and through the training given by the site I found and explored the great things with wonderopolis. I plan to use this site with my middle school students in many ways. I will use these creative facts to encourage critical thinking and responding each day as a warm up, they can read about the facts, respond in their journals and then discuss how this could relate to our curriculum. This site will be great to work with common core standards and make learning relevant to their lives. The erasers will be a great reminder that learning is never ending, that trial and error can be ok because it helps us develop and grow.

    • Hello, Wendy! We appreciate your comment! We think your ideas are great, and really like how you noted that Wonderopolis helps make learning relevant in your students’ lives! :-)

  9. There are a couple of ways I use the Wonder of the Day. When the wonder happens to be a compare/contrast topic, such as #248 – “How are Dolphins and Porpoises different” I have a student read the post independently. Then he will fill out a T-chart to record the differences learned and share that information with the class. On other days we read the question, watch the video, take a few minutes to jot/discuss what we think is the answer, then read the post as a class.
    I also have a link to Wonderopolis posted on my blog for easy access to all of the fantastic information!

    Traci Porter
    Lincoln Trail Elem. School
    N. Spencer School Corp.

    • We love the use of the T-charts to further learning of the compare/contrast Wonders, Traci! Thanks so much for being a friend of Wonderopolis and for encouraging your students to WONDER! :-)

  10. I plan to use Wonderopolis this year to introduce Thinkfinity to teachers. I am going to show them how they can use the vocabulary and questions to promote literacy. Also to use the Wonders as daily question and prediction starters.

    • Hello, Dorene! We really appreciate how you go the extra mile to share Wonderopolis with your fellow educators! The Wonder Words ARE a fun way to enhance vocabulary! Thanks so much for commenting on today’s ERASER Wonder! :-)

  11. I like to use Wonderopolis for my Challenge Question — I post “Wonders” and let my students go look up the answers — great for research and discovery of an amazingly Wonderful site !

    • What a great idea, Suzanne! Engaging students in research and discovery makes them more equipped to be life-long learners! Thanks so much for sharing! :-)

  12. As a school with a health focus, we take time out every day to share a healthy snack. While the food is handed out, we read over the Wonder together. As the kids eat, they talk about it at their tables. The discussions are always great! If the subject really strikes a chord, we tweet the kids’ opinions or spend some time writing in our journals about it. :)

    • What a GREAT way to bring Wonder into the classroom, Erin! Small group discussions can surely lead to bigger discussions and activities when Wonderopolis is part of the day! Thank you for commenting and sharing this with everyone! :-)

  13. I’m really excited about the inquiry and vocabulary aspects of Wonderopolis! I plan to use it for cooperative learning team building opportunities. Teams will read the initial question and work together to make predictions before reading the article. After teams share their ideas, they will read the article. Teams or individuals will use the vocabulary list to pick a word for their word collection. On occasion, we will also use the day’s topic as a springboard for further investigation!

    • We’re liking what we hear, Dee! These are AMAZING ideas for instilling Wonder in your students (both as teams and as individuals) in the classroom setting and beyond! Thank you for commenting today! :-)

  14. We just wanted to take a minute to say how absolutely WONDERFUL all of these creative ideas are! We appreciate all of our educator Wonder Friends and are grateful for the thought and time that went into your ideas! :-)

  15. I am So excited about using Wonderopolis this year for so many reasons! I will actually be using it tomorrow as an ice breaker for staff in my LIFE Tech Training. Teaching children with autism and other very special needs I am always looking for something that will help in telling stories, imagining, and using descriptive words. I can’t wait to use Wonderopolis and see what thoughts I can get my students to express!

    • Thank you so much for sharing your WONDERful ideas for engaging students with special needs, Andrea! Thanks also for sharing Wonderopolis with your colleagues…you’re a GREAT Wonder Friend!

  16. I just completed a Thinkfinity seminar on Monday so I have just recently been introduced to the marvels of Wonderopolis! I will inservice the other teachers about this great website and we will introduce Thinkfinity with Wonderopolis to all of the parents on Back to School Nite!

    • Hello, Sister Jane! We are so happy to count you as a new Wonder Friend! Thanks for leaving this great comment today and for sharing Wonderopolis and Thinkfinity with others! :-)

    • Hi, Mike! Welcome to Wonderopolis! We search for the best videos to illustrate each Wonder of the Day®, and thought yours was AWESOME! Thank you for leaving a comment and letting us all know there’s a real person behind the animation! :-)

    • Yes, Jacob! It IS made out of rubber! We thought it was interesting to learn that before rubber was used as erasers, people used rolled up pieces of bread! What was YOUR favorite part of this Wonder of the Day®?

  17. I started reading the wonderopolis recently and it amazes me everyday:) Now i am started looking at the past ones which i missed out. Thanks for sharing the wonderful information daily.

    • We’re SO GLAD you are visiting Wonderopolis, Elango! There are so many things to learn and explore here! Thank you for leaving us such a nice comment! :-)

    • We don’t think it’s weird, Troy, just a little different than what we’re used to in modern times! Technology is awesome, isn’t it? Who knows what we will be erasing our written mistakes with in the future? :-)

  18. I wish there was one eraser which would erase our parents’ mind so that they won’t remember our mischievous deeds. :P

    • That’s some really creative thinking, Aparajita! We’re pretty sure it would just be better for us all to make good decisions about our behavior, though, so we didn’t have to worry about needing to erase anything, don’t you agree? ;-)

      We hope you have a WONDERful day today! Thanks for always making us WONDER, laugh, think and SMILE with your comments! :-)

  19. This is a great little article. I’d love to see an electron microscope series of an eraser “picking up” graphite particles.

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 does an eraser work?
  • What is graphite?
  • Who invented the eraser?

Wonder Gallery

close up of a pencil eraser_shutterstock_55561411Vimeo Video

Try It Out

Erasers help us correct our mistakes, but did you realize they can also be used to make all sorts of interesting crafts? It’s true! Take a look at the following art projects, and choose one or more to try:

When you’re finished, email or send us a letter with a picture of your eraser art project!

Wonderopolis HQ
325 West Main Street, Suite 300
Louisville, KY 40202-4237


Still Wondering

Now that you’ve learned about erasers, let’s learn a bit more about pencils with Science NetLinks’ Build a Better Pencil lesson!


Wonder Categories/Tags


Wonder What’s Next?

Take a deep breath and get ready to plunge into tomorrow’s all-new Wonder of the Day!

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