This complete NGSS-aligned science unit explores how light travels, interacts with materials, and helps humans and animals see. Designed for Grades 1–4, this two-part unit follows the 5E model (Engage, Explore, Explain, Elaborate, Evaluate) and includes hands-on investigations, reading passages, vocabulary work, and aligned assessments. Students will learn: How light travels in straight lines (rays) What happens when light hits different materials (reflection, absorption, transmission) Why w