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. 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.

Step 2: Expected learning outcomes

Understanding the Problem

Demonstrates an understanding of the problem by describing the problem to be solved, including constraints or by exploring multiple or prior experiences.

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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.

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

Identifies multiple, diverse approaches to solve the problem.

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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

Analyses factors to choose a reasonable approach and implement it with precision.

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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.

A few things that are important to take in consideration:

  • The resources provided: A single kit or shared pile?
  • Understand if there is time to try out all the possibilities.

Emerging: Decide on a design.

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


Analyses the outcome by assessing whether the approach led to a reasonable solution.

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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 approaches and iterations during the process of solving the problem
  • 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 design and based on the answer point out where there should be an improvement or if another design would be a better fit.


Reflects on the problem solving process by identifying specific strengths and weaknesses of the selected approach(es).

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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 a strategy used to solve a problem
  • Describe something unexpected or learned
  • Reflects if a solution was appropriable 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.

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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