"The Number Race" is an adaptive game designed to improve number sense. We tested its effectiveness using a cross-over design in 53 low socioeconomic status kindergarteners in France. Children showed improvements in tasks traditionally used to assess number sense (numerical comparison of digits and words). However, there was no improvement on non-symbolic measures of number sense, suggesting that rather than being in number sense per se, the improvement was in number sense access; or links between symbolic and non-symbolic representations of number. Focused adaptive interventions such as this may contribute to reducing the socioeconomic gap in math achievement.