Introduction: In the present study we used a metaphorical representation in order to stimulate the numerical competences of six-year-olds. It was expected that when properties of physical action are used for mathematical thinking or when abstract mathematical thinking is grounded in sensorimotor processes, learning gains should be more pronounced in children with stronger motor capacities than in children with rather low motor capacities. Method: Thirty-four first grade children with a mean age of 6 years and 6 months participated in the experiment with a pre and posttest design. Therefore mouse handling precision, gross and fine motor performances and number line estimation was administered before and after the intervention with a digital number line. Results: In contrast to what was expected, children that performed below the median in a gross motor task benefitted significantly "more" from the intervention compared to children with scores above the median for such gross motor tasks. Discussion and Conclusion: These results do not only highlight the relationship between motor development and math learning but they also show that children with lower motor capacities are possibly more in need of a strong physical appearance whereby the possibilities for action are clearly visible, even in digital tools.