Lesson Plan

• Describe the sigmoidal shape of the oxygen‑haemoglobin dissociation curve and its relation to % Hb saturation.
• Explain how pO₂, pCO₂, pH, temperature and 2,3‑BPG shift the curve to the right or left.
• Interpret the Hill equation and the concept of P₅₀.
• Apply the curve to predict oxygen loading in the lungs and unloading in active tissues.
• Analyse the physiological significance of the curve during exercise and in pathological conditions.

• Projector or interactive whiteboard
• PowerPoint/slide showing the oxygen dissociation curve
• Printed worksheet with pO₂‑% Hb data and questions
• Graph paper or digital graphing tool
• Markers and whiteboard
• Handout summarising factors that shift the curve
• Clickers or online quiz platform for quick checks

Start with a quick think‑pair‑share: “Why does it matter how tightly haemoglobin holds onto oxygen?” Students recall prior knowledge that haemoglobin transports O₂ and CO₂. Explain that today they will explore the oxygen‑haemoglobin relationship, learn to sketch the curve, and identify the criteria for success – describing the curve, explaining shifts, and linking the shape to physiological function.

1. Do‑now (5’) – Short written question on O₂ transport; share answers.
2. Mini‑lecture (10’) – Present the sigmoidal curve, Hill equation and P₅₀ concept using slides.
3. Guided plotting (12’) – Students plot % Hb saturation vs pO₂ from the provided table on graph paper.
4. Interactive discussion (8’) – Examine factors that shift the curve; students predict right‑ or left‑shift for each factor.
5. Group activity (10’) – Given real‑world scenarios (fever, high altitude, exercise), groups annotate a blank curve with the appropriate shift.
6. Check for understanding (5’) – Clicker quiz with multiple‑choice questions on curve shifts.
7. Summary & exit ticket (5’) – Recap key points; pupils write one insight and one lingering question on a sticky note.

Re‑emphasise that the sigmoidal shape enables efficient loading of O₂ in the lungs and unloading in tissues, and that physiological variables modulate haemoglobin affinity. For the exit ticket, students state which factor causes a right‑shift and why. Homework: complete the worksheet calculating how a 2‑unit pH change would move the curve.