The Undergraduate Ambassador Scheme (UAS; http://www.uas.ac.uk/) enables university students to undertake a final year research project in association with a local school. At the University of Bristol we run UAS projects in which pairs of BSc students (a) design, deliver and evaluate biology lessons in the partner school and (b) design, implement and evaluate a complementary research project that includes collecting and analysing biometric data generated with/from the pupils. We describe a UAS research project designed to illustrate and extend the respiratory and cardiovascular components of the Salter-Nuffield Advanced Biology A-level curriculum. The impact of pupils’ height, weight and breathing pattern on the cardio-respiratory variables of vital capacity, breath-hold breaking point and resting heart rate (RHR) was compared to impact on these variables of regular exercise. One week before visiting our undergraduate physiology teaching lab, 65 A-level pupils took a test to evaluate their cardio-respiratory physiology knowledge and completed a modified Brunel lifestyle questionnaire1 quantifying their level of regular physical activity. They were then given worksheets explaining the experiments they would do in the lab and preparatory exercises to work through. In the lab, pupils rotated in small groups through three stations: (a) measuring vital capacity with a Benedict spirometer; (b) using ECG recording to measure RHR; (c) measuring their breath-hold (BH) breaking time at rest and after a period of voluntary hyperventilation while monitoring arterial oxygen saturation (SaO2) with a finger pulse oximeter. At the end of the lab session they completed the same theory test as before. Little correlation was found between the physiological variables and the subjects’ physical activity scores. However, there was strong correlation between height and vital capacity (r = 0.72; P < 0.001; n = 19). BH breaking time was increased from 39 s (SEM 2.6) to 65 s (SEM 5.1) after voluntary hyperventilation for 15 s (P < 0.001, Student’s t-test; n = 22) but SaO2 did not change. The results were discussed in the lab session and used to illustrate subsequent school lessons on cardio-respiratory anatomy and physiology delivered by the undergraduates. The average marks (out of a total of 11) for the pre- and post-lab physiology tests increased from 3.6 (SEM 0.36) to 6.8 (SEM 0.40); (P < 0.001, Wilcoxon signed-rank test; n = 60). The accompanying teachers gave very positive feedback on the benefits of the lab session for the pupils’ learning and engagement. We conclude that this type of BSc research project has significant benefits for the school pupils concerned; involves undergraduates in interesting and novel physiology research that also develops their communication skills; and fosters valuable links between universities and schools.