The document discusses the functions and key features of good science textbooks. It states that textbooks should aim to develop critical thinking skills in students. Some important functions include developing understanding of concepts, inculcating scientific attitude, illustrating concepts with real-world examples, and motivating students to investigate and discover new knowledge. Good textbooks are also well-organized, cover the entire syllabus, include thought-provoking questions and assignments, and provide references for further reading. They have clear printing and illustrations to help visualize abstract ideas.