Building Bridges

 Learn basic engineering concepts by designing your own bridge!

About the Activity

Bridge the gap! In this activity, kids will learn about the engineering design process and the basic mechanics behind building bridges while designing their own bridge. This activity is a lot of fun, and was created by Arianna Smith, a 4-H teen leader in STEM, in collaboration with the University of Tennessee. 


Grades: 6-12

Topic: Engineering

Time: 45 minutes


Brought to you by HughesNet and University of Tennessee Extension

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Some simple items will get you building:

  • 100 toothpicks
  • 4-8 books
  • Gummy candies (gumdrops and orange slices work well)
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Activity Steps
Follow these steps to build your bridge.

Before you begin, consider this: Bridges have been built for centuries, and with many different designs. According to Guinness World Records, the oldest bridge is the slab-stone single-arch bridge over the river Meles in Turkey, going back to 850 BC, meaning it is nearly 3,000 years old! 


No matter what they look like or how old they are, bridges all have one thing in common.


Find out what that is below: 


  1. Have you crossed a bridge recently? Have you ever thought of what would happen if all the bridges were closed?
Steps to complete the Building Bridges 4-H STEM Lab Activity
  1. Sketch out a design for your own bridge on paper. Choose a design from the pictures or of your own choosing that you think can hold the most weight. Did you know? Engineers follow five basic steps in the design process: 1) Gather information. 2) Develop possible solutions. 3) Make a prototype (the first model of a design). 4) Test the prototype. 5) Improve.
  2. Now get building using the toothpicks and the gummy candies! The goal is to build a bridge that can hold the maximum weight possible and the final structure must be portable! *For older youth, check out the bonus fun.How it works : By balancing compression and tension, bridges channel the weight or load of the bridge onto the main supports. When these two forces are balanced, there is no overall force to cause motion and do damage.
  3. Once everyone has finished their designs, place the bridges so that they span the gap between a stack of books or between tables. Fun fact: There are three kinds of bridges, which you saw in the PDF at the beginning of the activity: 1) arch bridge, which is a bridge with connections at each end that is shaped like a curved arch; 2) truss bridge, which is a bridge whose structure is supported by combined elements that form triangular units; and 3) suspension bridge, a bridge in which the weight is supported by cables that are connected to towers.
  4. Place one book at a time onto the bridges to see how much weight they can withstand. If comparing two or more bridges, be sure to use the books in the same order.
  5. Look at the graph of the engineering design process in the PDF activity and recap each of the steps you did in this activity. These are the same steps engineers use when creating real bridges!How do you know which style of bridge to build? There are lots of factors to consider, but the main one is how far the bridge needs to stretch. A very short span, such as over a small river, would likely use a beam or truss bridge. While a suspension or cable-stayed bridge could be used, they are more complex and expensive and would require much more support than would be needed for such a short distance, which is why suspension bridges are typically used to cover long distances.

Bonus Fun
Challenge older youth to complete their bridge(s) using different requirements, such as only 25 toothpicks, in 15 minutes, or so they can hold 5 books!

Reflection Questions
Questions for your kids and teens.

  1. After testing your bridge, what would you change about your design?
  2. What are some things you learned about the engineering design process?
  3. In what ways can you use the engineering design process in your life?
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Investigate and Explore
Take what you've learned to the next level.

The next time you see a bridge, see if you can identify which of the three basic designs it is patterned after. Consider: What about the surrounding environment led to the design?


If you enjoyed this activity, you may consider a career in civil engineering. Civil engineers design and build the kinds of structures that make travel possible: bridges, yes, but also tunnels and highways. 

4-H'er completes Building Bridges STEM Lab Activity

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