Building Straw Bridges – Fun and Hands-on STEM Activity for Kids

Children love building and designing. Take that love of construction and turn it into a fun STEM activity by building straw bridges.

Straw bridge building is an educational activity for children that naturally engages them in learning, understanding and enjoying science, engineering, technology and mathematics.

Hands-on learning activities, such as straw bridge building, help children generate ideas, experiment, test and refine their ideas, and have a positive impact on learning outcomes.

Straw Bridges is an exciting engineering project for kids that can keep them busy learning and crafting for hours. Help your kids take on the Straw Bridge challenge and unleash their inner engineering skills!

Content:

What is a bridge?

Types of bridges

Ideas for straw bridges

How to make a girder bridge from straws?

How to make a truss bridge from straws?

But before we get down to building a straw bridge, let’s delve into the basics of bridge building to understand the science behind these engineering marvels.

What is a bridge?

A bridge is a structure connecting two points. It allows people, vehicles and animals to cross natural or man-made obstacles such as rivers, valleys or railways. Today we also see bridges over roads – they are built to reduce traffic!

Bridges are important because they allow us to easily get from one shore to the other without going around or swimming across.

Types of bridges

Learning about bridges can be an exciting experience for children—it stimulates their creativity, problem-solving skills, and understanding of basic engineering principles.

Here are some common types of bridges:

1. Beam bridge

Girder bridges are one of the oldest and simplest types of bridges.

To build a girder bridge, you need a horizontal beam (vehicles drive over it) and support posts at each end to support the weight of the bridge. They are mostly used to cross small rivers, streams or gaps.

For example: Manchak Swamp Bridge, Louisiana

Related: Check out Science Trivia for a huge collection of science questions for elementary and middle school students.

2. Arch bridge

Arched bridges are not only aesthetically attractive, but also very economical. As the name suggests, arch bridges use reinforced arches to distribute and evenly support the load.

They rest on supports located at both ends of the curve. There are different types of arched bridges depending on the position of the span relative to the arch.

• Arch bridge with roadway – in this arch bridge, the roadway is completely above the arch. Example of an arch bridge with a carriageway: New River Gorge Bridge, West Virginia
• Pass-through arch bridge – in a pass-through arch bridge, the base of the arch is below the roadway, and the top of the arch rises above it. The Sydney Harbor Bridge is an example of this type of arch bridge.

The famous railway bridge over which the Hogwarts Express passes in the Harry Potter films is an arched bridge called Glenfinnan Viaduct. Can you guess what type of arch bridge this is?

3. Suspension bridge

Suspension bridges are a landmark invention; they are suspended on (thick) steel cables that support the weight of the bridge.

These steel cables, called suspension cables, are interconnected and supported by tall towers, firmly holding the roadway of the bridge.

Famous examples of suspension bridges are the Golden Gate Bridge and the Brooklyn Bridge.

4. Truss bridge

Truss bridges are perhaps the strongest and safest type of bridge. Bridges of this type use interconnected strong triangular frames known as trusses to support and balance the load on the spans!

Examples of truss bridges: Ikitsuki Bridge and Kingston-Rhinecliffe Bridge

Straw bridge building activity for students: ideas for a straw bridge competition

And now let’s dive into the practical adventure of building straw bridges! During this creative and educational activity, children will learn to make straw bridges and test their own ideas about their construction.

In this lesson, we will build two types of popular bridges:

• Beam bridge
• Farm bridge

While building a straw girder bridge is fairly easy and a great STEM activity for 4th graders, building straw truss bridges is a bit more complicated and time-consuming. Therefore, it is suitable as a STEM project for middle school students.

Quick tip: Don’t forget to add a healthy dose of humor with these science jokes and puns.

Beam bridge: how to make a bridge from straws step by step

Let’s start with a simple beam bridge to get the kids ready for this straw bridge activity. Making a simple beam bridge is a great pre-workout for a straw truss bridge project and will help children understand and appreciate the complexity of straw bridge construction.

Materials needed for a straw bridge:

• Drinking straws
• Scotch tape (preferably painter’s tape)
• Light test objects such as coins or paper cups

Instructions for making a straw bridge

Step 1: The first step in making such a straw bridge is to create a support for the beam. To make a support, take two straws and tape them together near one end to form a V shape.

Step 2: Next, add another straw to the support to form a pyramid shape. Make two pyramidal straw supports.

Step 3: In the last step, take two straws and tape them to the straw posts to form the spans of the straw bridge. You may need to adjust the straws to balance the girder bridge.

When everything is ready, place a paper cup on the span of the bridge to test its strength. You can put coins in the cup to test how much weight it can hold.

Truss bridge: how to make a bridge from straws and tape

Now let’s build a straw bridge to create a truss bridge model. This is one of the best straw bridge designs that uses triangular shapes of straw to give strength to the bridge structure.

Materials needed for a straw bridge

• Straws
• Scotch
• Scissors
• Ruler

Step-by-step instructions for building a straw bridge

Let’s bring our straw bridge to life by following these steps: You can divide the “straw bridge construction” into three different steps:

• Creation of the main structure.
• Side support beams.
• Collection of all elements.

Step 1: Creating a foundation.

Since the straws are very light, you need a strong base for the bridge! A strong base will ensure the stability of the bridge and help to avoid its unstable fall.

You can make the base by connecting vertical straws or gluing horizontal straws together. A horizontal straw bridge will be easier!

On the other hand, a vertical straw bridge base will be stronger because it will have more glue and volume.

• Horizontal Bridge: Straws are usually 15-20 cm long. You can make them longer by joining two straws together. This is easy because the straws bend. Use tape to connect them. You will need 5-6 long straws for the horizontal base of the bridge. Connect them horizontally and the base is ready!
• Vertical Bridge: The vertical bridge requires more time, but it is the strongest straw bridge construction. For this, you will need two long straws (30-40 cm) and several small straws (all cut to exactly 8 cm). Place the long straws parallel to each other, 8 cm apart. Now start sticking small straws vertically between the two long straws until you have completely closed the gap between them.

We decided to make a horizontal base.

Step 2: Creating Truss Patterns

You will need four triangular trusses!

• Cut straws 10 cm long for a triangular structure.
• You need to connect three straws to make one farm.

Step 3: Making the upper part of the truss bridge

To simplify the construction of the bridge, tape together 5-6 straws as well as the base to make the upper girdle of the truss bridge.

Step 4: Assembling the bridge parts.

Attach the trusses to both sides of the bridge base so that they stand vertically on it. Finally, glue the top beam of the bridge to the trusses to complete the bridge structure.

That’s it! Your straw bridge is ready! Place light objects on the bridge, such as a toy car, a small rubber band, a coin, increasing the weight to test its strength and find out at what weight the bridge will collapse.

Pay attention to areas that show signs of weakness and consider how you can improve the structure and strength of the bridge. Adding additional trusses to the structure is one way to increase its strength.

Related: Combine this fun activity with other fun engineering activities for kids.

Remember, this STEM bridge building contest is about having fun, learning, and discovering the magic of DIY bridge building. There is no one right way to build straw bridges!

Give free rein to your creativity by experimenting with different designs and techniques, turning your straw bridge into a masterpiece. Add more straws or change the layout to find the best straw bridge design that will satisfy the engineer in you.

Final thoughts…

Teaching children the basics of construction and engineering is a useful and educational activity. It allows them to expand and explore new horizons of human possibilities.

While making this straw bridge, don’t forget to tell the children about the different types of bridges and how and why they came to be.

Learning becomes interesting when accompanied by experiments and practical activities. At the same time, plan a short trip with the children to the nearest bridges in your city – they learn faster by examples!

Source: Straw Bridges – Fun and Educational STEM Activity for Kids