Geometry and nest air

Audience: Upper-secondary education, Biology and Physics. Suggested time: 40–45 min. Status: technical draft; Biology and Physics teacher review pending. Starting lesson: Entrances and ventilation (entradas-ar). Resources: WebGL browser, paper or spreadsheet, and laboratory access. Follow the common preparation.

Objective

Distinguish concentration, gas quantity and circulation; compare two open systems without assuming an opening guarantees homogeneous oxygenation.

BNCC

Proposed association: EM13CNT101, EM13CNT301 and EM13CNT302. See the mapping and official source in the general guide. Teacher review is needed.

Steps and records

1. In 5 min, predict how a second opening could affect chamber gases.
2. Open Entrances and ventilation and check Air in the galleries: A has one entrance; B has two. Both start at model O₂ 19% and CO₂ 1.2%.
3. Record the initial diagram, minimum/maximum concentration and population. Equal concentration does not imply equal quantity: the second segment changes volume.
4. Advance one model day, pause and record the same A/B indicators, including accumulated respiration. Repeat at days 3 and 5 without changing parameters.
5. In 10 min, explain a difference or its absence, distinguishing exchange with the atmosphere from internal redistribution. Export and restore the backup.

Discussion questions

• Do two openings necessarily create a strong current in every chamber?
• Is comparing percentages sufficient to compare total quantity?
• Can a nest receive oxygen and still contain lower-oxygen regions?

Annotated answer guidance

Circulation depends on the network, resistance and gradients; an extra entrance does not ensure uniform improvement. Percentages require volume to indicate model quantity. Respiration consumes O₂ and produces CO₂ while boundaries allow exchange. Accept conditional results supported by extremes and the diagram. The pair changes both opening and local geometry, so it does not separate those effects.

What the model does not represent

An approximate compartment network, without molecular dynamics or full CFD. Prepared percentages are not real nest measurements, safety references or recommended animal-rearing conditions.

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.