Objective: To evaluate cardiopulmonary resuscitation (CPR) skills performance and retention in schoolchildren aged 8 to 12 years following instruction by their teachers and with the guidance of a school nurse using paediatric manikins. Design: Descriptive simulation trial. Method: A school nurse provided support to six schoolteachers as they taught a modified 40-minute CPR course. Pupils were shown an out-of-hospital cardiac-arrest recognition video followed by a CPR simulation using paediatric manikins. 117 schoolchildren aged 8 to 12 years received the training. Both the schoolchildren and teachers completed a survey before and afterwards. Children completed an out-of-hospital cardiac-arrest recognition test and a 1-minute CPR test 1 week later. Results: After training, schoolchildren increased their self-efficacy as rescuers (8 ± 2 vs 10 ± 2; p < 0.001). Irrespective of age differences, 74% of schoolchildren performed the entire out-of-hospital cardiac-arrest recognition sequence correctly. Children aged 11 to 12 years and 10 to 11 years performed higher quality CPR (49% and 47%, respectively) compared to 8 to 9 year olds (14%, p = 0.008 and p = 0.014). Children aged 11 to 12 years outperformed younger children aged 8 to 9 years with respect to compression depth (48 ± 6 mm vs 43 ± 5 mm, p = 0.008) Conclusion: Schoolchildren's teachers, who were guided by a nurse using paediatric manikins, taught children aged 10 to 12 years to perform high-quality CPR. We suggest integrating paediatric manikins as part of children's CPR training as feedback from successful CPR performance increases motivation and confidence to act as a rescuer as well as improves skills retention.