Many citizen science projects deal with high attrition rates. The Dutch Great Influenza Survey is an exception to this rule. In the current study, we conducted an online questionnaire (N=1610) to investigate the motivation and learning impact of this loyal, active participant base. Results show that the desire to contribute to a larger (scientific) goal is the most important motivator for all types of participants and that availability of scientific information and data are important for learning. We suggest similar projects seek (social) media attention regularly, linking project findings to current events and including the importance of participants' contribution.

Citizen science is one of the most dramatic developments in science communication in the last generation. But analyses of citizen science, of what it means for science and especially for science communication, have just begun to appear. Articles in this first of two special issues of JCOM address three intertwined concerns in this emerging field: The motivation of citizen science participants, the relationship of citizen science with education, and the implications of participation for creation of democratic engagement in science-linked issues. Ultimately these articles contribute to answering the core question: What does citizen science mean?

Since 2009 Vetenskap & Allmänhet (Public & Science, VA) coordinates an annual mass experiment as part of ForskarFredag — the Swedish events on the European Researchers' Night. Through the experiments, thousands of Swedish students from preschool to upper secondary school have contributed to the development of scientific knowledge on, for example, the acoustic environment in classrooms, children's and adolescents' perception of hazardous environments and the development of autumn leaves in deciduous trees. The aim is to stimulate scientific literacy and an interest in science while generating scientific output. The essay discusses how the mass experiments can contribute to encouraging scientific citizenship.

Success stories of citizen science projects widely demonstrate the value of this open science paradigm and encourage organizations to shift towards new ways of doing research. While benefits for researchers are clear, outcomes for individuals participating in these projects are not easy to assess. The wide spectrum of volunteers collaborating in citizen science projects greatly contributes to the difficulty in the evaluation of the projects' outcomes. Given the strong links between many citizen science projects and education, in this work we present an experience with hundreds of students (aged 15–18) of two different countries who participate in a project on cell biology research — Cell Spotting — as part of their regular classroom activities. Apart from introducing the project and resources involved, we aim to provide an overview of the benefits of integrating citizen science in the context of formal science education and of what teachers and students may obtain from it. In this case, besides helping students to consolidate and apply theoretical concepts included in the school curriculum, some other types of informal learning have also been observed such as the feeling of playing a key role, which contributed to an increase of students' motivation.

When entering the research world, Early Career Researchers (ECRs) may encounter difficulties building a good reputation for their research, its quality and the research results. Open access is the movement that could assist ECRs to: (a) widely disseminate their scholarly outputs, (b) demonstrate the research and societal impact of their work and, (c) organise online research portfolios that can be accessed by all researchers, as well as prospective employers.

During the last decade universities have developed policies and infrastructures to support open access to publications but now it is time to move a step forward. There is an increasing demand for accessing data supporting the research results to validate and reproduce them. Therefore universities have to be prepared for this new challenge that goes beyond dissemination because it requires a strategy for managing research data within institutions. In this paper I will try to give some hints on how to deal with this challenge that can be framed in the new open science movement aimed at providing openness in all the whole cycle of research.

Open science is the most recent paradigm shift in the practice of science. However, it is a practice that has emerged relatively recently and as such, its definition is constantly-shifting and evolving. This commentary describes the historical background of open science and its current practice, particularly with reference to its relationship with public engagement with research.

Open Science may become the next scientific revolution, but still lingers in a pre-paradigmatic phase, characterised by the lack of established definitions and domains. Certainly, Open Science requires a new vision of the way to produce and share scientific knowledge, as well as new skills. Therefore, education plays a crucial role in supporting this cultural change along the path of science. This is the basic principle inspiring the collection of essays published in this issue of JCOM, which deals with many subjects ranging from open access to the public engagement in scientific research, from open data to the social function of preprint servers for the physicians' community. These are issues that go along with the targets of the FOSTER project (Facilitate Open Science Training for European Research) funded by the European Union, which has provided interesting food for thought in order to write this commentary.

Teaching mathematics in informal settings is a relatively new phenomenon, but it has gained more attention due to the recent changes in the society. The aim of the present quantitative study was to compare the learning outcomes of Latvian and Swedish 12-year-olds when they visited a science centre mathematics-art exhibition originally designed in Estonia. The results showed that in general, prior knowledge of the exhibition contents was the strongest predictor of post-test results in both countries but that mathematical thinking skills and self-concept had a small added value in explaining the post-test results. The results of the study give some of the first pieces of evidence of the effectiveness of out-of-school mathematics teaching in a science exhibition context, providing a good basis for further studies.

For decades, particle physicists have been using open access archives of preprints, i.e. research papers shared before the submission to peer reviewed journals. With the shift to digital archives, this model has proved to be attractive to other disciplines: but can it be exported? In particle physics, archives do not only represent the medium of choice for the circulation of scientific knowledge, but they are central places to build a sense of belonging and to define one's role within the community.