https://www.khanacademy.org/math/cc-fourth-grade-math-essentials/xcc712acd200f2b6c:plane-figures 2026-06-30T17:10:42.766349973Z Plane figures In this unit, you'll get to dive into the exciting world of plane figures! You'll learn all about lines, line segments, and rays. You'll even get to experiment with angles and find out how they make shapes look different. Plus, you'll get to explore some cool concepts like parallel and perpendicular lines. unit