Perennialist teachers mainly emphasize:

The correct answer is Abstract ideas. Perennialist teachers mainly emphasize abstract ideas, universal truths, and timeless principles. This philosophy holds that education should focus on developing intellectual and moral virtues through the study of enduring works of literature, philosophy, history, and science. They believe in teaching students about the great ideas that have stood the test of time, aiming to cultivate a rational mind and an understanding of human nature and fundamental knowledge, rather than focusing on contemporary problems or vocational skills. The curriculum is typically subject-centered and highly academic.

• Practical education (B) is more characteristic of philosophies like Progressivism, which emphasizes learning by doing and real-world problem-solving. Perennialism views practical skills as secondary to intellectual development.
• Theoretical concepts (C) are a part of Perennialism, but 'abstract ideas' better captures the essence of their focus on universal, non-empirical, and conceptual truths rather than just contemporary theories.
• Methods (D) are important for any teaching philosophy, but 'abstract ideas' describes the core *content* emphasis of Perennialism, which is the key distinction here. Perennialist methods often involve didactic teaching and Socratic dialogue to explore these ideas.