Galaxy zoo: Science content knowledge of citizen scientists.

We report the results of a large-scale study of the state of science content knowledge of volunteers in Galaxy Zoo ( www.galaxyzoo.org ), an online citizen science project in which public volunteers classify galaxies in an effort to benefit cutting-edge astronomy research. We were interested in whether participating in Galaxy Zoo leads to any increase in participants' astrophysical content knowledge. To assess volunteer content knowledge, we examined the responses of 1476 Galaxy Zoo volunteers to 32 conceptually challenging multiple-choice questions. We looked for any relationships between participants' assessment scores and the number of galaxies classified upon answering the first assessment question, the number of galaxies classified between their first response and their final response to the assessment, and the length of time since they first created their Galaxy Zoo account. All relationships were of small effect size. These results suggest that participation in the project's central galaxy classification task, in and of itself, is not associated with increased astrophysical content knowledge. We strongly recommend that future studies of online citizen science environments examine how volunteers take advantage of opportunities to develop their knowledge and skills outside of the self-contained central task, especially in the context of opportunities for interactions with other volunteers.