Spatial skills are consistently linked to mathematical reasoning, and are sensitive to intervention. One important spatial skill is spatial scaling. We evaluated whether (1) a playful scaling game might promote learning by providing feedback during play, and (2) spatial scaling is related to number-line estimation (NLE) based on the mutual reliance on relative magnitude reasoning. Forty-eight children, ages 5.5-8.3, completed a playful scaling game and a NLE task. Results show that children improve from the first to second half of the task, especially for more difficult trials and for the lowest performing children. In addition, scaling and NLE relate when controlling for age and vocabulary. Similar improvement on the task and relations to NLE were observed in a conceptual replication (N = 52). These results provide support for further study of improving spatial scaling in children, with the possibility to test whether scaling could support related mathematical skills as well.