Social constructivism is a learning approach in which students actively construct their own knowledge by way of experiences and interactions with others. As such, it is important to highlight both individual and group-based reflection practices in pre-service teacher training as a key aspect for improving teaching practice. This paper presents the results of the design and implementation of a training programme of 7 sessions (8.5 h of class participation plus 25 h of personal homework) for pre-service secondary school science teachers, who were asked to design a gamification resource and an e-rubric to evaluate it. Subsequent improvement of this e-rubric was enhanced by performing different reflection activities at key moments. The programme was carried out by 50 Spanish pre-service teachers from Málaga (Spain). Data collection centred on the e-rubrics designed, the emotions experienced and the possible transfer to real-life practice performed six months later. The impact of reflections on the evaluation was studied by analysing the evolution of the categories proposed by the participants for the e-rubric at different times, with marked changes being found during design and preparation of the gamification resource, and only very minor changes post-implementation. In addition, a group-based criteria consensus session favoured a more in-depth reflection. Interest was the main emotion experienced by pre-service teachers, especially during preparation and use of the resource. The programme also had a marked impact on transfer of the e-rubric into practice, as did the designed resource, although to a lesser extent.