# Trails, wind and local decisions

**Audience:** Upper-secondary education, Biology and Physics. **Suggested time:** 35–40 min.
**Status:** technical draft; Biology and Physics teacher review pending.
**Starting lesson:** Pheromones and wind (trilhas-vento). Resources: WebGL browser,
paper or spreadsheet, and laboratory access. Follow the [common preparation](README.md).

## Objective

Distinguish transport of a chemical signal, local decision and an agent’s trajectory.
Formulate a hypothesis that an observation could contradict.

## BNCC

Proposed association: EM13CNT202, EM13CNT203, EM13CNT301 and EM13CNT302. See the
mapping and official source in the [general guide](README.md). Teacher review is needed.

## Steps and records

1. In 5 min, draw predictions for a trail with crosswind and another without wind.
2. Open **Pheromones and wind**. Record seed, A wind 0/B 1.5 u., and day 0.
   Both scenarios have identical artificial trails and prepared colonies.
3. Check top view and **Pheromones**. Switch A/B without resuming; draw the initial
   signal, entrance and food positions. Add no interventions.
4. Resume for one model day at 1×, pause and compare A/B. Repeat until day 3.
   Record day, scenario, apparent trail direction/extent and stored food.
5. Use 10 min to distinguish field observation from worker displacement. Follow
   one worker in first person as a supplement, without treating its individual
   trajectory as the colony average. Export records and restore the backup.

## Discussion questions

- Are chemical distribution and individual trajectory the same thing?
- Can a signal spread and weaken at the same time?
- If food does not increase in B, does that necessarily contradict transport?

## Annotated answer guidance

The field can change through diffusion, evaporation, advection and new deposits.
Choices are probabilistic and local; a worker does not follow a fixed path.
Reserve differences also depend on collection, consumption and geometry. Accept
no measurable difference in the recorded interval. Compare initial and final
fields and justify conclusions using drawings, without imposing a winner.
Wind also affects air, so this pair does not isolate chemistry alone.

## What the model does not represent

Concentration and wind have abstract units. The initial trail is prepared;
the image is not a chemical analysis and the nest is not a calibrated species.
Observed divergence does not demonstrate mathematical chaos.

## Learning evidence

Submit a hypothesis, comparable records with days/units, a data-supported
conclusion and one limitation. Use the general guide’s rubric; there is no
required outcome.

## Teacher review

Pending. No teacher or class was consulted to approve this guide. Record review
and adjustments in the appropriate form before treating it as validated.