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Supported by Rolls-Royce

Bear’s bridge-building mission

Work together and show that your team can create a bridge capable of helping Bear complete his jungle journey.
Plan a session with this activity

You will need

  • Pens or pencils
  • Scrap paper
  • Scissors
  • Tables
  • Tape measure
  • Craft materials (for example, tissue paper, pipe cleaners, stickers)
  • Weights, like coins
Bridge type cards
PDF – 508.9KB
Materials price list
PDF – 69.1KB
Two Scouts balance on a log, whilst Buddy the dog watches on.

Before you begin

  • You may wish to plan this activity across two sessions. Introduce everyone to bridges and the science involved in making them. Then, in the first session begin work on designs. In the second session, build and test the bridges.
  • You can request a STEM Ambassador to help deliver science, technology, engineering and maths (STEM) activities in the programme. To get started, go to the STEM Ambassador website and register as a youth and community group, so you can share requests for support.
  • Cut out the squares from the 'Bridge type cards' for each sheet.

Set the scene

  1. Set the scene with this mission brief:
  1. Explain to everyone that the task requires them to come up with a design of a bridge to span a gap, using only the materials listed. If there’s time (doing everything may take two sessions), factor in the weight of each bridge, the budget each team has and include costs for the materials.
  2. Before everyone splits into groups, everyone should agree on some design feature rules for the bridges – namely, how wide the gap they need to span is. Everyone should come up with a replica river to the one Bear needs to cross and agree upon how wide it is. This will show each team how long their bridge needs to be.
  1. Everyone also needs to agree upon what must’ve happened for a bridge to have failed. This could either be total collapse of the bridge or a certain amount of deflection in the centre of the bridge.
  1. The group should then discuss the different forces that act on a typical bridge. These are an important factor if you’re designing bridges that need to be able to bear a load without bowing or collapsing. Show everyone the image below to get them thinking about this:
Two people standing on a bridge that's bowing under their weight. There are arrows showing the different forces acting, compression towards the centre of the bridge, tension away from the centre and the reaction force from the ground either side holding the bridge up.

Build your bridge

  1. Now that everyone’s clear on the kind of bridges they need to make, everyone should split into small groups of three or four people. Give each group their set of squares from the 'Bridge type cards' to pair up, and give them some inspiration as they try to come up with a bridge design of their own. Groups should use pens, pencils and paper to sketch their own designs.
  2. Each group should settle on a design by having each person create their own, individual designs, and then pooling them together, so that the best ideas can be seen by everyone and agreed upon. This is known as ‘divergent-convergent’ thinking. Hopefully, this should allow groups to produce bridges that use a combination of everyone’s best ideas.
  3. Once a finished concept has been drawn, teams should decide which materials will work best for their bridge design, how big they should make it and how the different parts should be made. Each person should be assigned specific tasks, whether that’s managing the budget, sourcing materials, construction or testing.
  4. Begin building the bridges, with each person in each team taking responsibility for their tasks.
  5. Once the building is completed, bridges should be tested to see that they meet the criteria set out by all the groups for all the groups. Bridges should be weighed to check that they’re light enough to be portable. Budgets should be checked against the total budget to see that no-one has overspent. Set up bridges one at a time on the replica river made earlier. The bridge should span the full width.
  1. Groups should take back their bridges and think of at least one thing they can change or improve to help the bridge meet the agreed-upon criteria. This may be a feature that failed under testing, or came close to failing. Ideas should be tested independently before being added to the finished bridge.
  2. Test the improved bridges to see how they do this time around. Groups need to decide whether their changes made a difference – for better or worse. In any time that’s left, groups should keep testing, trying new ideas or features and check their findings, until they can draw conclusions on the best possible materials, scale and features of their design.


Building bridges to a specification required technical problem-solving skills. Think about which was the best design, why it was better and how you decided what to improve. Were there any other groups who designed a better bridge?

Teams assigned one another different roles to help with the bridge build. Did this give everyone in the group a more-or-less-even amount of work? Was this the most efficient way for you to work, or should different people have done different tasks?



Supervise young people appropriately when they’re using scissors. Store all sharp objects securely, out of the reach of young people

Sharp objects

Teach young people how to use sharp objects safely. Supervise them appropriately throughout. Store all sharp objects securely, out of the reach of young people.

Glue and solvents

Supervise young people appropriately when they’re using glue and solvent products. Make sure there’s plenty of ventilation. Be aware of any medical conditions which could be affected by glue or solvent use and make adjustments as needed.