Here's a nice anchor chart for studying vocabulary related to lines.
The 4th Grade May-niacs: Lines and Angles
Teaching With a Mountain View: Angles, Angles, Angles!
Here's a lesson plan that includes a foldable and sorting activity on lines, line segments, rays, and angles.
Teaching Tales Along the Yellow Brick Road: Geometry Unit and Symmetry Activity- 4th Grade
4.MD.7 FREE 4th Grade Angle Word Problems + lots more CCSS Resources
4th Grade Frolics: Reflection Bugs! Students make symmetrical bugs out of their names on either side of a folded piece of paper.
The perfect addition to your Geometry Unit!