These are bounded opportunities, not learner attainment. Partial and blocked source requirements remain so.

• partial: Describe the structure of the human gas exchange system (trachea, bronchi, bronchioles, alveoli) and explain how the mechanism of breathing — using pressure changes from rib and diaphragm movement — moves air in and out of the lungs

  Bounded objective: Trace air to alveoli and explain breathing using pressure change. Simplified anatomical/pressure model only; no clinical lung-function or physical breathing assessment.

• partial: Labels a diagram of the lungs showing trachea, bronchi, bronchioles, and alveoli

  Actual branch diagram labelled; visual/nonvisual evidence distinct.

• partial: Explains that breathing in lowers air pressure in the chest and air rushes in

  Volume/pressure mechanism taught and recalled; no breathing test.

• partial: Describes how the structure of alveoli (large surface area, thin walls, good blood supply) aids gas exchange

  Area/thin barrier/blood supply linked to gas exchange, selected feature explanation.

• partial: If {{name}} took a deep breath after running, could they explain what's happening in their lungs — how the air gets in, where the oxygen crosses into the blood, and how carbon dioxide leaves?

  Try offers taught-diagram-recall for the bounded objective; it does not establish every part of the source assessment. Simplified anatomical/pressure model only; no clinical lung-function or physical breathing assessment.

• Simplified anatomical/pressure model only; no clinical lung-function or physical breathing assessment.