Introduction: Physical education (PE) can contribute to total daily physical activity (PA) among children. In consequence, the Spanish Ministry of Education, Culture and Sport has developed 16 teaching units focused on increasing PA levels during PE lessons, called "Unidades Didácticas Activas" (UDA; Active Teaching Units). Objectives: The goal of this study was to compare whether children participating in UDA lessons spent more time in moderate-to-vigorous physical activity (MVPA) than children participating in traditional lessons. Design: Quasi-experimental design. Methods: A total of 355 children (8-9 years old, 53.9% boys) from 7 schools in Granada participated in the study. Students were divided into two groups: a traditional PE group (n=204) and a UDA group (n=151). Time spent in MVPA was assessed using tri-axial accelerometers. Results: Time spent in MVPA was higher in the group engaged in the UDA lessons compared to the group that received traditional lessons (13.6 vs 15.2 minutes, p=0.021, Standard Error=0.27). The percentage of children who met international MVPA recommendations was similar for both groups (UDAs: 12.7% and traditional: 13.2%, p=0.504). Conclusions: UDA lessons and their methodology favoured greater participation in MVPA compared to a traditional PE approach. It will be important to change PE methodology (including duration, frequency and focus) to achieve MVPA goals.