Multisensory learning paradigms can positively affect learning of various cognitive skills (Shams & Seitz, 2008). Furthermore, integrating congruent motor movements (i.e. motor-enrichment) during acquisition can be superior to only audio-visual acquisition in academically related learning (Mayer et al., 2015). We conducted a six-week cluster-randomized intervention study of motor-enriched mathematics for Danish schoolchildren (n= 148, age= 7.5 ± 0.02). We investigated whether low intensity motor activity congruently integrated during solving of math problems could enhance math performance. Three groups were included: 1) Control group with normal math teaching, CON (used pencil, paper but refrained from additional motor activity). 2) Fine-motor-enriched-group, FM (motor-manipulating LEGO bricks integrated in the lessons). 3) Gross-motor-enriched-group, GM (full-body movements integrated in the lessons). In FM and GM, all math classes (six lessons pr. week) had motor activity integrated in the math lessons and the teachers of all groups followed a detailed description for the conduction of the lessons. This aimed at ensuring homogeneity between groups concerning the taught themes. The children were tested pre- (T0) and post- (T1) intervention. We used a standardized 1st grade math test including 2nd grade questions to avoid a potential ceiling effect. Additionally, we conducted a phonological- and spatial working memory test and a test of executive functioning to investigate potential mediators of academic performance. Furthermore, electroencephalography (EEG) was measured during mental arithmetic at T1. All groups improved from T0 to T1. Interestingly, the improvement in GM from T0-T1 was significantly larger than FM 1.76 ± 0.70 (P = 0.03). Additionally, a subgroup analysis was performed, extracting data from children with learning difficulties, according to national standards (n= 44). In this subgroup no significant differences was observed in the improvements from T0-T1 between the three groups (P > 0.05). Conversely, in normal-achieving children, GM improved significantly more from T0-T1 than CON 1.78 ± 0.70 (P = 0.04) and FM 2.14 ± 0.69 (P < 0.01) from T0-T1. We conclude that gross-motor enrichment can increase math performance and that this effect might be more pronounced for normal-achieving children compared to children with learning difficulties. Future work should seek to investigate the mechanisms behind the observed behavioral differences.