The Marvels of Bridges: Free Online STEM Class

When I was in the public school classroom, one of my favorite units was an engineering and design challenge – Toothpick Bridges. It required little teacher preparation, kept the kids focused and engaged, and best of all, the kids LOVED it!

When we first began homeschooling, my son was fascinated with bridges. I knew we had to build toothpick bridges. He was pretty young so I made a few modifications to the original lessons and jumped into the unit study. You can read about their first experience in my previous post, Building Toothpick Bridges.

Bridges: Free Hands-on, Online STEM Class @EvaVarga.netNow that they are older and summer is upon us – I thought it would be fun to revisit this challenge. In fact – I want to provide this opportunity to all of YOU!! 

I have put together an eBook, Engineering Marvels: Bridges, that includes a materials list, templates, supplemental lesson plans, bibliography, and additional resources. The online course whereby I will also provide access to instructional videos to walk your children through the process of creating a toothpick bridge of their own will take place in July.

This would be an excellent activity for a co-op!

I’m very excited and wanted to let you know of this opportunity today so you can plan ahead. So gather a few friends together and get ready for a friendly competition.

This opportunity is available FREE to my newsletter subscribers. If you already subscribe – just watch for the next newsletter for the download links and video access codes.

If you don’t yet subscribe, do so today. You will have lifetime access to a multitude of additional science printables and resources.


Science Milestones: The Golden Gate Bridge

One of the seven wonders of the modern world, the Golden Gate Bridge was the life mission of an engineer who had never designed or overseen the building of a suspension bridge. At the time of its construction the Golden Gate Bridge was the longest suspension bridge in the world, built hundreds of feet above the dangerously churning waters of the entrance to San Francisco Bay, the Golden Gate. 

goldengatebridgeJoseph Strauss, a bridge builder from Chicago, had been visiting San Francisco for several years to supervise work on a small drawbridge, one of four hundred he had built around the world. But Strauss’s ambitions far surpassed any work his firm had ever attempted.

Bridges have long been an interest to us a family and we enjoy spending the weekend in the big city of San Francisco whenever possible. We watched the new Bay Bridge as it was constructed but the red hue of the Golden Gate Bridge has always captivated us.

Biography

straussJoseph Baermann Strauss was born in Cincinnati, Ohio on the 9th of January 1870. He loved poetry and hoped to pursue a career in the arts like his mother, a pianist, and his father, a painter and writer. Though he never became a fine artist, he would help create one of the most famous bridges in the world.

Following his college graduation, Strauss worked as a draftsman for the New Jersey Steel and Iron Company, and the Lassig Bridge and Iron Works Company in Chicago. Seven years later, he was named principal assistant engineer in the firm of Ralph Modjeski, a Chicago engineer. While working for Modjeski, Strauss developed his trademark “bascule” drawbridge design. Strauss’ bascule was a utilitarian structure, practical but unlovely.

Strauss eventually left Modjeski’s company, forming the Strauss Bascule Bridge Company in 1904. A prolific engineer, he constructed some 400 drawbridges across the U.S. Yet he dreamed of building “the biggest thing of its kind that a man could build.”

In 1919, San Francisco’s city engineer, Michael O’Shaughnessy, approached Strauss about bridging the Golden Gate, the narrow, turbulent passage where San Francisco Bay meets the Pacific Ocean. Strauss campaigned tirelessly over the next decade to build the bridge. He faced enormous opposition from the “Old Guard” — environmentalists, ferry operators, city administrators, and even the engineering community. Yet in November 1930, a year into the Great Depression, voters at last supported a bond issue for Strauss’ bridge. The ambitious project finally had its green light.

Strauss alienated many people in his quest to build the structure, his first suspension bridge. Obsessed with claiming credit as the span’s creator, he minimized the contributions of Charles Ellis and Leon Moissieff, the two visionaries who actually worked out the significant engineering challenges of building the bridge.

On May 27, 1937, the bridge opened to the public. Returning to his other great love, poetry, Strauss composed verse for the occasion, exulting, “At last, the mighty task is done.” It would be the last mighty task of his life. Exhausted, Strauss moved to Arizona to recover. Within a year, he would die of a stroke.

Bring it Home

  • Read about some of the opposition to the bridge. Then prepare a poster expressing either support for, or opposition to, the Golden Gate Bridge project. Your poster should reflect one of the arguments made for or against the bridge at the time it was being debated. Illustrate your poster with a drawing of the benefit or harm the bridge would bring to your community.
  • During his campaign, Strauss had bribes distributed to members of the San Francisco Board of Supervisors to secure their support for the project. Imagine that you are a young newspaper editor in San Francisco at the time and you have just learned about these bribes. How could you respond in a way that would be in the city’s long-term interest? Write an editorial condemning the bribes or praise the project as necessary regardless of the maneuvers that might be necessary to make it happen.
  • Read about Irving Morrow, about the man who designed the Golden Gate Bridge’s distinctive Art Deco features. Find a photo of another building or other object designed in the Art Deco style and explain what you like about the style. Alternatively, choose another bridge or building structure, find out what style of architecture it represents, and explain why you like it.
  • Coordinate a toothpick bridge building competition amongst your friends.
  • People love suspension bridges for many reasons: their beauty, their utility, their mathematical elegance, their long spans, or even for the regional bragging rights they confer. Research other suspension bridges around the world and create a PowerPoint or a webpage to share with others what you learned.
  • Learn how the Golden Gate Bridge was financed. What is a bond? Why do governments issue bonds? Why do voters have to vote to approve a bond issue? What is “collateral” and what did these six counties use as collateral for the bonds?
  • Visit the Golden Gate Bridge and the Golden Gate Bridge Pavilion yourself and learn more about the construction of this Strauss’ first suspension bridge.
  • While in San San Francisco, enjoy the Golden Gate Treasure Hunt in honor of the 75th Anniversary.

Science Milestones

Building Toothpick Bridges .. a Lesson Plan

We have an opportunity this year to participate in our first homeschool science fair.  The kiddos have been fascinated with bridges for a long time so I knew immediately what project we’d undertake … Toothpick Bridges.  I’ll share with you my toothpick bridges lesson plan with you here.Buddy's Design

Capture Their Attention

Before we began construction, we read again the delightful picture book Bridges Are to Cross by Philemon Sturges.  We then used the internet to make observations of many modern bridge designs, particularly those we were familiar with here in Oregon as well as those we’d seen first hand in San Francisco.  I set up a little demonstration to show what structure was strongest … squares or triangles … using just drinking straws taped together at the corners to form a square and a triangle.

Strength in Design

I then gave the kids graph paper with which I instructed them how to begin designing bridges of their own.  They came up with several designs each – some of which weren’t feasible for toothpicks.  They then selected a design that would most easily be reproduced with toothpicks and we proceeded with construction.

toothpick bridge

Building Bridges with Toothpicks and Glue

In the classroom setting, I used to provide each team with a predetermined amount of money with which they would need to purchase their material … lumber (toothpicks) and welding material (school glue).  However, here at home, their imagination and thereby their design were the only limitations.

testing bridge strength

Testing Bridge Strength

We tested the strength of the bridges by suspending a gallon-sized milk jug beneath the bridge with a pencil.  Initially, we had used a smaller container but it turned out to be too small to contain the weights.  We then began to slowly add weights (marbles & metal washers) to the container.  When we ran out of weights, I began to slowly pour water into the jug.

toothpick bridge collapse

We continued in this way until the bridges finally collapsed or gave in to the pressure.  In the classroom, the eminent collapse and destruction of the bridges was always a highlight and was met with cheers and shouts of enthusiasm.  Here at home, I hadn’t anticipated the the big tears that we experienced.

toothpick bridge

In the end, the two bridge far surpassed our expectations.  Buddy’s design took on 16 pounds before it finally succumbed to the weight.  Sweetie’s design held more than 19 pounds!  Had she had more trusses along the roadway that supported the pencil, we hypothesis that her bridge could have supported more weight as her bridge remained intact with the exception of the road that gave way.

toothpick bridge

The kiddos are looking forward to presenting their experiment on Friday at the science fair.  Buddy is even talking about building more toothpick bridges – but he says he doesn’t want to test them.  “I don’t want to break my bridge.”

Engineering Marvels: Bridges

For more details and links to do this project with your kids, check out my Engineering Marvels: Bridges unit study.

Bridges Are to Cross :: Book Sharing Monday

My kiddos have always been intrigued by bridges. “When are we going to see the big bridge?” is a frequent question as we travel over the Cascade and Coast mountain ranges on our way to Grandma & Papa’s house in North Bend. The McCullough Bridge, the mile-long span across the Coos River, is their indication that we have arrived.

With our recent vacation in San Francisco and seeing first hand two of the most infamous bridges (The Golden Gate Bridge and Oakland Bay Bridge), the kids have been increasing interested in bridges. At the library last week, we discovered another gem, stumbling once again upon a book in our library by chance (many of the books we’ve most enjoyed have been found at the library on display – we haven’t actually searched the online catalog to find them).

Bridges are to Cross by Philemon Sturges is a great introduction to bridges. Everyone knows bridges are to cross — to get to the other side. But did you know that some bridges carry llamas loaded with firewood, some let people dance over lazy rivers, some were forts for defending castles, and some were crossed by emperors and popes? From a simple log to woven webs of steel, bridges reflect our values, our lifestyles. Feast your eyes on these bridges from around the world and you will come to realize that crossing is only one reason for having a bridge.

The text introduces the reader to many of the most famous bridges in the world, of which our favorites were:

  • Apurimac River Bridge, Peru (rope suspension bridge)
  • Cnococheague Aqueduct, Maryland USA (stone arch bridge)
  • Segovia Aqueduct, Spain (stone arch bridge built by the Romans)
  • Salginatobel Bridge, Switzerland (3-hinged concrete arch bridge)
  • Brooklyn Bridge, New York USA (wire suspension bridge)

Each bridge introduced also includes a brief statement identifying the bridge type… from arch to suspension to rope bridges… providing a building block for those interested in learning more about the architecture of bridge design.

Like most picture books, what intrigued us perhaps more than the words were the three-dimensional illustrations, all painstakingly created with intricately cut paper by artist Giles Laroche. The illustrations were created on a variety of paper surfaces through a combination of drawing, painting, and papercutting. These cut-paper illustrations of bridges are complex and exquisite; their texture and depth astonishing. Paper-cutting or paper-piecing is fast becoming one of our favorite art forms.Upon reading this book, the kiddos are even more interested in bridges and have been building bridges in our living room to cross the span between the couch and the coffee table. They started out using their bodies to create simple beam bridges and have now advanced to using their Taekwondo belts to create suspension bridges. The little guy even identified it correctly, “Mommy! This is a suspension bridge like the Golden Gate!”

I may have to change plans once again and do the toothpick bridge unit sooner than I anticipated. If I do so, I hope you will all join us for a virtual bridge building contest. Let me know if you are interested!!!

Bridges are to Cross is an excellent book for budding engineers, future artists, and especially new readers!