The Triangle Game (Systems Thinking)

The Triangle Game is a systems thinking exercise from The Systems Thinking Playbook by Linda Booth Sweeney and Dennis Meadows. It immerses participants in a system of simple interdependencies: each person adjusts their position based on two secretly chosen individuals. The group observes that an individual movement can produce collective readjustments, sometimes leading to stabilization. The exercise serves to open a concrete discussion on cascading effects, leverage points, and the impossibility of controlling a complex system from a single point.

Walkthrough

1. 1

   Prepare the space and set the framework

   3 min

   The facilitator clears a large space of tables, chairs, and bags on the floor, then invites participants to stand dispersed throughout the area. They announce: "We are going to experience a living system, without talking and without trying to win. Your safety is paramount: walk, do not run, keep your distance." Participants position themselves in a scattered manner. This setup helps avoid collisions and makes collective movements visible.

   Tip — Take thirty seconds to check for blind spots, cables, and obstacles: in this game, participants often look at their references rather than the ground.

2. 2

   Secretly choose two reference points

   2 min

   The facilitator asks everyone to mentally choose two other people in the group, without naming them, looking too obviously, or warning them. They specify: "These two people will be your reference points during the exercise. Keep this choice secret until the end." Each participant memorises their two references. The secrecy is essential: it prevents explicit coordination and creates an invisible network of interdependencies.

   Tip — If someone hesitates, tell them to simply choose two people they can see well; avoid having the group wait for a perfect selection.

3. 3

   Initiate the movement of equidistance

   5 to 8 min

   At the signal, the facilitator gives the full instruction: "Move to be equidistant from your two reference points. You can aim to form an equilateral triangle, or more simply, remain equidistant from the two chosen individuals. Everyone moves at the same time, silently and walking." Participants continuously adjust their positions. The facilitator observes without correcting strategies, as the interest lies in seeing the system self-organise.

   Tip — Calmly remind participants "equidistant, not aligned" if several people position themselves between their reference points; do not provide a geometric solution, let the learning occur through the body.

4. 4

   Observe potential stabilisation

   3 to 5 min

   The facilitator allows the movement to continue as long as the group is still seeking their place. If the movement slows down, they gently say: "Continue to adjust until you feel that your distance to the two reference points is correct." The group may stabilise completely, partially, or remain in motion. The facilitator invites everyone to internally note what they feel: ease, frustration, dependence on the movements of others.

   Tip — Do not seek to achieve perfect stabilisation: the absence of stability is also a very rich result for discussing systemic dynamics.

5. 5

   Move a single person

   3 to 5 min

   When the group seems slowed down or stabilised, the facilitator approaches one person and asks them to move a few steps to another spot in the space. They announce only: "We are going to change one element of the system; the rules remain the same." The moved person then adjusts their position like the others, and the whole group reacts according to their own references. Participants notice that the movement of a single element can trigger a cascade of movements.

   Tip — Choose a person who is relatively central in the group's visual field: the propagation effect is often more visible for observers and players.

6. 6

   Stop the exercise and return to calm

   2 min

   The facilitator stops the exercise with a clear voice: "Stop, stay exactly where you are and look at the configuration of the group." They allow a few seconds of silence for everyone to observe the final positions. Then they invite participants to relax their posture and return to a circle. This transition prevents moving too quickly to analysis and helps anchor the lived experience before verbalising it.

   Tip — Ask participants to remain still before returning to the circle: the mental snapshot of the system greatly aids the debrief.

7. 7

   Debrief the systemic learnings

   7 to 10 min

   The facilitator opens the debrief with observable facts: "What did you see moving? What triggered your own movements?" They then connect the responses to the concepts of interdependence, cascading effects, and leverage points. They emphasise that no one was controlling the whole, even though everyone followed a simple rule. The group finally translates the experience to their organisations, projects, or ongoing changes.

   Tip — Start with sensations and observations before concepts; otherwise, participants will intellectualise and lose the strength of the physical experience.

Variants

• Conduct a first round with the strict instruction to seek an equilateral triangle, then a second round with the simpler instruction to remain equidistant. Compare in the debrief the effect of the level of demand on fluidity and stabilisation.
• Designate a few external observers during the round. They do not know the chosen reference points and only note the movements, slowdowns, and restarts, then share what they saw in the debrief.
• Replay a short round after the first debrief, asking participants to consciously notice their dependencies. This replay allows distinguishing what changes when the system is better understood, even if the rules remain the same.