The document discusses principles for selecting instructional materials at the elementary level. It defines instructional materials as any resources used by teachers to help students learn. Key principles include teachers being familiar with the materials, selecting materials that are appropriate for students' capabilities and learning styles, and choosing materials based on their learning outcomes rather than just availability or ease of use. The document also outlines different types of instructional materials like printed texts, non-projected materials, projected materials, audio materials, and community resources.