PURPOSE: Physically Active learning (PAL) and Movement Breaks (MBs) are popular methods for encouraging increased Physical Activity (PA) within curriculum time. Both have also been claimed to enhance pupil’s cognitive and academic performances. However, existing research evidence is inconsistent in finding support for such claims and there are no studies directly comparing the two methods. Consequently, this study investigated the acute effects of lessons taught using PAL or incorporating MBs on pupil’s Cognitive and Academic Performances (AP) and PA Levels. METHOD: 355 children (aged 8-10 years) from three schools in Northern England participated in a cluster-randomised trial. Classes of pupils were assigned to participate in one of the three types of, 45 min long, mathematics lesson (Lesson-type: PAL, MB or Traditional). Physical activity during lessons was measured using accelerometery and pre- and post-lesson participants completed a battery of standardised assessments assessing of their Maths Fluency (measure of AP) and Cognitive (Attentional) Control. RESULTS: Compared to Traditional (sedentary) lessons, PAL and MB lessons were associated with pupils being significantly more Moderately to Vigorously Physically Active during lesson time (95% CI: +9.86 to 11.06 min). PAL lessons also reduced time spent sedentary by a significantly larger margin than lessons incorporating a MB (95% CI: -16.60 to 21.70 min). However, variation over time in Maths Fluency and Attentional Control measures were not significantly moderated by Lesson-Type, with Bayes Factors indicating evidence in favour of null hypothesis (All Time X Lesson-Type interactions had a BF10 ranging from 0.29 to 0.04). CONCLUSIONS: Both PAL and MBs effectively increase student’s PA levels during curriculum time. These benefits do not come at the expense of academic or cognitive performances but neither do these outcomes appear acutely enhanced.