Background: An emerging field of research indicates that the use of learning environments other than the classroom can improve pupils’ academic achievement in several subjects, including their skills in mathematics.

Purpose: The aim of this study was to investigate the association between Education Outside the Classroom (EOtC) and pupils’ skills in mathematics.

Methods: This explorative, quasi-experimental study involved schoolchildren (aged 9–13 years) from 15 Danish public schools who participated in EOtC over the course of a school year. The mathematical skills of pupils from 23 EOtC maths intervention classes (n=421) and 12 EOtC non-maths comparison classes (n=198) were measured at the start and end of the 2014–2015 school year.

Results: Both groups showed improved maths skills; however, we found no significant difference between the EOtC maths and the comparison groups.

Conclusion: The results indicate that, in this explorative study, moving maths teaching outside the classroom neither harmed nor improved pupils’ mathematical skills. These results and implications for research are discussed.