Long ago, ancient Romans placed stone pillars called “obelisks” along the sides of roadways. Typically, the stones were placed a mile apart. Each “mile stone” was given a unique number, serving as a mile marker.

Today most people are familiar with the word “milestone,” but we use it in a slightly different way. Our modern-day use was inspired by the Romans’ ancient practice. Just as Roman mile stones helped travelers know how far they had come on their journey, our modern use of this expression does the same thing.

Instead of marking our journey on an actual road, however, milestones mark significant events in our lives. People reach milestones throughout their lives. You may not realize it, but you have already reached many milestones in your life, too.

As a baby, you reached milestones when you learned how to roll over, crawl, stand up and, finally, walk. Children celebrate many milestones as they grow up: learning to read, riding a bicycle without training wheels, getting — and losing — your first tooth and going to school for the first time are just a few examples.

You’ve got your whole future ahead of you — and that means many more milestones ahead! Graduating from high school or getting your driver’s license will be major milestones. If you ask your parents, they’re sure to tell you their wedding day and the births of their children were happy and important milestones in their lives.

Wonderopolis is celebrating a WONDERful milestone today: This is our 100th Wonder of the Day!

What makes the number 100 so special? If you pay attention, you will find 100 popping up everywhere from stove tops to piggy banks. As the first three-digit whole number, 100 is considered important around the world.

Water boils at 100° C. There are 100 pennies in a dollar. A century is 100 years. If something is 100 percent, it’s considered complete or full.

People have given special recognition to 100 to mark achievements or accomplishments for hundreds of years. From 100th anniversary celebrations to 100th birthdays, 100th episodes to 100th wonders, 100 marks a milestone — and we’re just getting started!

Over the past 100 days, we have explored why flamingos are pink, how horses sleep standing up and what bees do in the winter. We’ve learned why chili peppers are spicy and why cheddar cheese is orange.

We’ve taken flight with the Wright Brothers, Amelia Earhart and a flock of birds in a flying “V.” We’ve jiggled Jell-O, twisted fairy tales and invented superheroes to save the world.

We’re so glad you’ve joined us to celebrate our 100th Wonder of the Day milestone. We hope you will take some time to explore and reexplore Wonders of the Day #1 to #99.

Do you have a favorite? Send us an email, post a comment in the section below or send us a message on Facebook or Twitter to let us know which Wonder of the Day is your favorite so far and why.

As for Wonders of the Day #101 to #200, we want to know what you’ve been wondering about. Would you like to find out what a narwhal is or why bats sleep upside down? Maybe you’ve been wondering how boats stay afloat or how glass is made.

Tell us what questions are on your mind! Your curious question could inspire a future Wonder of the Day.


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    • We think Mrs. Caplin and her AWESOME class ROCK! Thank you all for your great comments and enthusiasm for Wonderopolis! We’re kind of partial to this Wonder, ourselves! :-)

  1. Hello,
    Thanks so much for making this interesting post! I can’t believe that milestones came from the ancient Romans. I learned that they put stones a mile apart to mark each mile. They gave each stone a special number to mark a spot on the journey! I made the connection that their milestones marked a special spot on the journey, and our milestones mark a special spot in our life journey! I was wondering, did they just count up by ones by we do (1,2,3,4,5…) for their milestones or did they make up special numbers because of the special spot on the journey? 2 new or interesting vocabulary words I learned are ancient (which means old) and obelisk (which means pillar). Thanks so much for this awesome wonder!
    Team Unger #11

    • WOW, Team Unger #11! You sure WONDERed a lot about milestones today, and we think that’s GREAT! We like the connection you made to real life milestones, too! We’re not sure if people way back then counted the stones the way we would count them today. That’s going to take a bit more WONDERing! Thanks so much for this SUPER comment! :-)

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Have you ever wondered…

  • What is a milestone?
  • What milestones have you already reached in your life?
  • What future milestones are you looking forward to achieving?

Wonder Gallery

Wonder #100 - Milestone ImageVimeo Video

Try It Out

Ready to take a road trip back through time? You’ve experienced many personal milestones during your lifetime so far.

A great way to record these memorable moments is by creating a personal milestone memory book. Get ready to get scrappy!

This is a fun project to work on with family members. Talk about major moments in your personal life and create a scrapbook page for each milestone.

Perhaps you’ll want to create a page for your first birthday, your first lost tooth and your first day of kindergarten. You can even use copies of old family photos to document each important event.

If you need some help getting started with your personal milestone memory book, check out Debbie Hodge’s helpful hints on how to Scrapbook “Your” Story to capture and mark your personal milestones and accomplishments.


Still Wondering

What milestones do you see in your future? Reaching your long-term goals for the future means laying a solid financial foundation today. Visit EconEdLink’s The ABCs of Savings lesson to learn more about how to set goals and save for the future!


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Wonder What’s Next?

Today’s wonder took you back in time; tomorrow’s wonder will take you forward and backward in the same sentence. It may even leave you asking, “Was it a car or a cat I saw?”

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