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Help me prepare and run the exercise below. First ask for my participant count, time, setting, access needs and intended result. Check these against the stated limits. Use the supplied rules and materials. Explain any proposed changes before using them, and label them as adaptations. Do not invent source claims or require personal disclosure. Give me one step at a time when I say start. I manage the people, physical activity and clock; do not claim to observe the room. Ask me what happened before choosing a next step.

Reference revision: 381fb3fb9839d1335e78265eb1634983fead492b7a1b9155be92173a67ff0276

# The Strongest Bridge

Teams design and construct a paper bridge spanning exactly 50 centimeters. Each structure is timed during construction and loaded with weights until failure to calculate an efficiency score.

**Time:** 55 minutes. The source outlines 40 minutes for build stages alone; UWT allocates 55 minutes total to allow structured briefing, testing, and debrief.
**People:** 6 to 24. Small teams of 3 to 4 participants

## Choose this exercise

**Purpose:** Test team planning, rapid execution, and trade-offs under constraints by comparing construction speed against structural load capacity.
**Use it when:** Use during team workshops or project kickoffs to examine how groups handle planning versus execution and balance speed against quality.
**Skip it when:** Skip if the space lacks sturdy tables or testing ledges, or when groups need purely analytical discussion without physical manipulation of materials.

## Materials and tools

- For each team: 20 sheets of standard paper, 10 index cards, 15 paper clips, 1 roll of clear adhesive tape, 1 manual stapler
- 1 measuring tape or ruler per team
- 1 digital stopwatch or phone timer per team
- Testing station materials: 2 stable tables or desks spaced exactly 50 cm apart, 1 metric scale (or pre-weighed items), and progressive weights (e.g., 250g, 500g, and 1000g water bottles or sandbags)
- 1 flipchart and marker to record scores

## Before participants arrive

1. Mark a clear 50 cm span between two level testing surfaces using masking tape.
2. Prepare separated material bags for each team: Bag A for planning (paper, index cards, paper clips) and Bag B for construction (tape, stapler, additional paper).
3. Weigh and label the test weights in grams in advance.

## Say this to open

Your challenge today is to design and build a freestanding bridge that spans a half-meter gap and holds as much weight as possible. Your score is your total supported weight in grams divided by your build time in seconds. A faster build raises your score, but only if your bridge holds the load. We will begin with planning, move to timed construction, and then test every bridge publicly.

## How to run it

### 1. Briefing and Role Setup (5 minutes)

Divide participants into teams of 3 or 4. State the core constraint: the bridge must rest on two surfaces 50 centimeters apart without taping it to the tables. Explain the scoring formula: Score equals grams supported divided by construction seconds. Ask each team to assign a builder, a timer, and a materials lead.

### 2. Concept Planning (20 minutes)

Distribute Bag A (paper, index cards, paper clips) and rulers. Teams sketch ideas, test small folds, and agree on a blueprint. No tape or staples may be used during this phase. At the 18-minute mark, prompt teams to finalize their plan. Bridges must not be fully pre-assembled during planning.

### 3. Timed Construction (10 minutes)

Hand out Bag B containing tape and staplers. Start team timers. Teams build their structure across their desk gap. When a team finishes, their designated timer stops their clock and records the elapsed seconds on their score card. Construction must stop for all teams at the 10-minute cap.

### 4. Public Load Testing (12 minutes)

Gather around the central testing station. Each team places their bridge across the 50 cm gap. The facilitator or team member adds weights in increments of 250 grams, pausing 3 seconds between additions. Record the maximum weight held before collapse or slipping off the gap. Compute each team's score.

### 5. Structured Debrief (8 minutes)

Review the score board. Ask two whole-room reflection questions, taking three to four observations from across the groups before closing.


## Debrief questions

- Where did your design deviate from your original plan once the timer started?
- How did the balance between speed and structural strength shape your decisions during the build?
- If you had one additional round with the same materials, what specific structural or workflow change would you make?

**Finished output:** A completed scoreboard showing construction time in seconds, maximum weight supported in grams, and the final efficiency score for each team's bridge.

## Remote

For fully remote teams, each participant builds individually at home using matching supplies (20 sheets paper, 1 tape roll, 10 paper clips). Each person spaces two books or chairs 50 cm apart and films their test live on camera, loading identical canned goods or filled water bottles with verified weights. Time and weights are entered into a shared digital spreadsheet.

## Hybrid

Hybrid delivery is split by site. In-person members form physical building teams at their venue. Remote participants form their own remote teams or pair up remotely to run digital planning and timekeeping while one remote member executes the physical assembly locally. A stationary camera streams the central testing station so online participants can see every load test live.

## Access and participation choices

- Participants who prefer not to handle small materials can take the role of timekeeper, structural quality checker, or score calculator.
- Anyone may choose to observe the load test from a comfortable distance rather than placing heavy weights.

## If the session gets stuck

**A team's bridge collapses immediately with the first weight, resulting in a score of zero and frustration.**

Acknowledge the structural failure neutrally as standard testing data. Highlight the team's build speed or novel geometry and invite them to diagnose the failure point during debrief.

**Teams attempt to tape their bridge down to the testing tables.**

Remind the room before testing begins that anchors or tape to the base tables are prohibited; the bridge must rest entirely under its own friction and balance.


## Terms used here

- Efficiency Score: The mathematical result of dividing the total grams supported before collapse by the construction duration in seconds.
- Clear Span: The unsupported distance between the two interior edges of the testing surfaces, set strictly to 50 centimeters.

## Sources and adaptation

Observed in the Participatory Methods library under the title 'The Strongest Bridge' (2025).

Retained the core mechanic from Participatory Methods: a 50 cm bridge tested to failure, scored by weight divided by time. Expanded the 40-minute activity window to 55 minutes to allow proper briefing, realistic public testing, and debrief. Replaced vague materials with clear per-team allocations and explicit measurement rules.

[Participatory Methods](https://participatorymethods.com/activities/the-strongest-bridge/)

Current run sheet: https://unitedwetransform.com/exercises/the-strongest-bridge/