Appealing to the crowd gives access to valuable sources of knowledge and opinion. Amateurs and experts exchange ideas, generate and discuss content, solve problems, vote for the best solutions, and raise funds. A classic example of the crowd in action is Wikipedia, the online encyclopaedia co-created and continually updated by the public. Other examples include citizen science activities such as identifying birds and classifying galaxies. However, we are not yet using the wisdom of the crowd to its full potential as a resource in education and for learning. Possible applications of crowdsourcing in education include collecting and curating teaching resources, letting students share and discuss their work online, and providing opinions and data for use in projects and research studies. Crowdsourcing can lead to research that is initiated by the general public, rather than by scientists, and the opportunity to seek solutions to real-life problems. Designing and supporting such activities offers a way to scale them up. It also teaches the public to think scientifically, to appreciate sciences, and to support the work of scientists. Approaches need to consider the quality and validity of the contributions that are made by the public; the crowd may be wrong!