They might be multidisciplinary (more likely in elementary schools) or single-subject (commonly science and math). Some projects involve the whole class, while others are done in small groups or individually. For example, Perrault and Albert[13] report the results of a PBL assignment in a college setting surrounding creating a communication campaign for the campus' sustainability office, finding that after project completion in small groups that the students had significantly more positive attitudes toward sustainability than prior to working on the project.