There is growing interest in the introduction of Einsteinian concepts of space, time, light and gravity across the entire school curriculum. We have developed an educational programme named 'Einstein-First', which focuses on teaching Einsteinian concepts by using simple models and analogies. To test the effectiveness of these models and analogies in terms of student attitudes to physics and ability to understand the concepts, various short and long interventions were conducted. These interventions were run with Years 6 to 10 academically talented and average IQ students. In all cases, we observe significant levels of conceptual understanding and improvement in student attitudes, although the magnitude of the improvement depends on age group and programme duration. This paper reports an unexpected outcome in regard to gender effects. We have compared male and female outcomes. In most cases, independent of age group, academic stream and culture (including one intervention in Indonesia), we find that female students enter our programmes with substantially lower attitude scores than males, while upon the completion of the programme, their attitudes are comparable to the boys. This provides a compelling case for widespread implementation of Einsteinian conceptual learning across the school curriculum. We discuss possible reasons for this effect.