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Truss Bridge: Problem Solving

Gain and demonstrate proficiency in problem solving with this bridge exploration.

In this exploration, we’ll show how to scaffold situations for your students to develop and demonstrate problem solving with a Strawbees Truss Bridge!

Step 1: Problem presentation

The problem is how to build a bridge that connects two cardboard boxes separated by a specific distance. You can give this distance in any metric system including in straw lengths. We suggest it to be around 3 and half blue straws.

It’s also important to know how much weight the bridge can hold. It's important to remember that hanging a weight on straws can damage it and we recommend either making a cardboard platform or hanging the probe on connectors.

Each of your students should receive enough material to complete the task.

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Step 2: Expected learning outcomes

Understanding the Problem

Make sure students understand they are expected to describe clearly what were the problems they were solving while building the bridge. Incentivize them to look at multiple ways to describe the problem and to draw from previous knowledge to make sense of what’s happening. This is an excellent chance to talk about forces and trigonometry, for example.

There are 2 major problems designed for this activity:

  • Bridge from original activity or example must be too small to cover the gap distance. We recommend three and a half blue straws.
  • There are no specific instructions about how to make the load test, except it should not fold or break the straws.

Emerging: Identify designed problems.

Proficient: Can describe the design challenges and other problems and constraints.

Possible Approaches

It's easy and quick to iterate over ideas with Strawbees and it might be tempting to just start building but making a plan is important to demonstrate the ability to solve problems systematically. There are many ways in which the bridges can be built differently, here are some groups of possibilities:

  • Different sizes by using different straw sizes
  • Mixed materials such as cardboard and wooden sticks
  • It could have a cantilever or pillars to help the structure

Emerging: Identify a few ways to build the bridge.

Proficient: Can describe and categorize a wide range of approaches that can be taken.

Choosing and implementing approach

Strawbees a very practical, fast-paced and iterative building process but make sure your students understand they are expected to demonstrate the ability to make educated guesses based on facts to choose their approach. Students are expected to take in consideration how much material is available and how much time they have to build.

Emerging: Decide on a design.

Proficient: Chose an approach that that fits the constraints of the problem and execute it with precision.


After implementing the suggested approach, make sure your students understand they are expected to articulate whether their approach worked or not as expected and why. Students are expected to compare the performance of different approaches during the process as well as rank bridge performance and explain the parameter for judgment.

Emerging: Identify if the bridge behaved as expected.

Proficient: Understand and communicate about the efficiency of a specific design and if there could be an improvement.


Your students should be able to explain where their bridges are excellent and where it failed or could be improved. Students are expected to identify and communicate about the strategies they used to achieve their goals, describe something unexpected or recently learnt and reflect if the solution was appropriate beyond the designed problems.

Emerging: Point out a problem solving situation

Proficient: Understand the systematic process of problem solving they went through and point out a situation they might start using problem solving to tackle.

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Step 3: Instructions and assessment

We provide a full step by step instructions on how to build a basic Truss Bridge and a variety of other examples for inspiration. We also have other Activities that might provide other insights on the bridge making.

You can have the instructions available, give a lecture on how to build it, build together with the whole class or all the previous combined. Experiment with what type of instructions and assessment works the best with your group.

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