Who leads the flock?

What will you explore?

Reynolds, 1987

Local choices can create collective motion.

How does it work?

Watch a 90-second cinematic explanation, or explore a story that pauses so you can change its central mechanism. Inspect the source evidence, compare outcomes and resume the narration. This free Lesson Worlds adaptation needs no account or download; younger learners may want help from a parent or teacher.

Inside the cinematic story

1. Who leads the flock?

   Local choices. Collective motion.

2. Enter one bird's world.

   Separation · velocity matching · local centering

3. Take one rule away.

   Same start. Different rule.

   Take control: Which replay would you like to inspect? Separation on · Separation off

4. Change how they coordinate.

   Velocity matching on / off

   Take control: Which coordination rule should the replay use? Matching on · Matching off

5. A model has boundaries.

   Original adaptation · not biological validation

6. The pattern belongs to the group.

   Enter the flock. Inspect the rules.

Discuss the evidence

Before starting, explain what you think this claim means: Local choices can create collective motion. After exploring, choose one stage above and describe what its model helps you see. Separate what you observed in the adaptation from what the original researchers measured.

Read the original publication for its methods, evidence and limitations. Ask which part of the explanation the interactive model leaves out, and what additional evidence you would need to test the claim yourself.

Original teaching simulation, not the paper's code or animal observations. Fixed seed; spherical neighborhoods; weighted steering; soft enclosure; no obstacle avoidance. Reynolds used directional perception and prioritized steering. Wing animation is decorative. No collision-free guarantee or biological validation.

Original research

Flocks, Herds, and Schools: A Distributed Behavioral Model

Craig W. Reynolds · SIGGRAPH 1987 · Computer Graphics 21(4), 25–34 · 1987

Educational adaptation by Lesson Worlds. Not affiliated with Craig Reynolds, ACM or SIGGRAPH. The original publication may have its own access terms.