Final answer:
Johann Friedrich Herbart's three main contributions to education are the development of a scientific pedagogical method, emphasis on moral education, and the psychology of education.
Step-by-step explanation:
Johann Friedrich Herbart is not directly mentioned in the reference materials provided. However, using general knowledge about Herbart's contributions to education, one can note that he was pivotal in the establishment of pedagogy as an academic discipline. Three main contributions from Herbart include the five-step teaching method, which aimed to provide a scientific structure to educational practice; his moral education theory, where he emphasized the importance of moral and character development in students; and his psychology of education, where he explored how instruction and learning could be influenced by psychological factors.
Although Herbart's contributions were significant, they should be viewed in the context of his time and alongside other educational reformers mentioned in the reference material who advocated for public education, moral and disciplinary teaching methods, and education as a path to social reformation.