We investigate the development of scientific content knowledge of volunteers participating in online citizen science projects in the Zooniverse (http://www.zooniverse.org). We use econometric methods to test how measures of project participation relate to success in a science quiz, controlling for factors known to correlate with scientific knowledge. Citizen scientists believe they are learning about both the content and processes of science through their participation. We don't directly test the latter, but we find evidence to support the former — that more actively engaged participants perform better in a project-specific science knowledge quiz, even after controlling for their general science knowledge. We interpret this as evidence of learning of science content inspired by participation in online citizen science.

Volunteer water quality monitors represent the intersection between citizen science and environmental stewardship. Understanding what motivates participation will enable project managers to improve recruitment and retention. This survey of 271 volunteers from eight water quality monitoring organizations in the U.S. found the strongest motivators to participate are helping the environment or community and contributing to scientific knowledge. No variation by gender was found, but younger volunteers have different motivations and preferences than older volunteers. Volunteers value the communication of tangible results more than recognition or reward.

Online citizen science projects have demonstrated their usefulness for research, however little is known about the potential benefits for volunteers. We conducted 39 interviews (28 volunteers, 11 researchers) to gain a greater understanding of volunteers' motivations, learning and creativity (MLC). In our MLC model we explain that participating and progressing in a project community provides volunteers with many indirect opportunities for learning and creativity. The more aspects that volunteers are involved in, the more likely they are to sustain their participation in the project. These results have implications for the design and management of online citizen science projects. It is important to provide users with tools to communicate in order to supporting social learning, community building and sharing.

Community-based water monitoring (CBWM) provides essential baseline information on watershed health and engages the public in science, but those involved often encounter barriers to informing environmental management. We conducted qualitative interviews with watershed group coordinators and government counterparts from four CBWM organizations to explore instances where CBWM successfully influenced governmental decision-making. Our findings show that the level of rigor for quality standards, inclusion of volunteers, available resources, and desired goals are important considerations when designing community-based monitoring programs. Integrated program designs that include adequate quality standards and engage volunteers are more apt to maximize resources and realize both scientific and educational goals.

In recent years, citizen science has gained popularity not only in the scientific community but also with the general public. The potential it projects in fostering an open and participatory approach to science, decreasing the distance between science and society, and contributing to the wider goal of an inclusive society is being explored by scientists, science communicators, educators, policy makers and related stakeholders. The public's participation in citizen science projects is still often reduced to data gathering and data manipulation such as classification of data. However, the citizen science landscape is much broader and diverse, inter alia due to the participation opportunities offered by latest ICT. The emergence of new forms of collaboration and grassroots initiatives is currently being experienced. In an open consultation process that led to the "White Paper on Citizen Science for Europe", the support of a wide range of project types and innovative forms of participation in science was requested. In this paper we argue for mechanisms that encourage a variety of approaches, promote emerging and creative concepts and widen the perspectives for social innovation.

This commentary considers the topics of humour and online settings. Both have received increasing attention amongst researchers and practitioners of science communication, and both raise numerous questions around the role of informality and enjoyment in the spread of information. However, online settings also provide a great range of data with which to address these questions. Here I suggest that close consideration of technical infrastructure plays an important role in this data collection. I shall do so using case studies drawn from two popular participatory websites, reddit and Facebook, which display contrasting attitudes towards using humour. I argue that these attitudes are partly products of the different tools provided by the pages for users to show appreciation, which affect the appearance of content on the websites. I also suggest that these tools allow users to appreciate jokes in multiple ways, and by extension might provide researchers with methods for assessing different forms of engagement.

Interviews were conducted with 110 marine users to elicit their salient beliefs about recording marine species in a citizen science project. The results showed that many interviewees believe participation would increase knowledge (either scientific, the community's, or their own). While almost half of the interviewees saw no negative outcomes, a small number expressed concerns about targeting of marine species by others, or restrictions on public access to marine sites. Most of the people surveyed (n = 106) emphasised the importance of well-designed technological interfaces to assist their data collection, without which they would be unlikely to engage in the project.

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.

Citizen science has proven useful in advancing scientific research, but participant learning outcomes are not often assessed. This case study describes the implementation and tailoring of an in-depth assessment of the educational impact of two citizen science projects in an undergraduate, general education course. Mixed-methods assessment of citizen science within a college classroom demonstrates that public participation in scientific research can positively alter attitudes towards science. The timing and type of assessments yielded significantly different results and qualitative assessment provided depth and context. However, disentangling the impact of the course from participation in the projects is the biggest challenge.

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.