Bring science to life with this engaging, mystery‑based unit where students become Particle Detectives! Through four high‑interest cases, students investigate real‑world phenomena, analyze evidence, build particle models, and write CER explanations — all while mastering the NGSS standard 5‑PS1‑1: Develop a model to describe that matter is made of particles too small to be seen.This unit makes abstract particle ideas visible, concrete, and fun. Each case includes student pages, evidence boards,