Roots of Reason
Roots of Reason
rootsofreason.org
what is it, and how do you know?
Anchor Chart · Grade 4 · 4.G.A.1

Lines and Angles

Points, segments, rays and lines, and what happens where two of them meet.
1Point, Segment, Ray, Line
pointsegmentraylineAABABABAABABAB
A dot means it stops there.
An arrow means it keeps going.
2An Angle Is an Opening
ABCvertex
angle ABC
angle CBA
Two rays from one point make an angle.
The vertex letter always sits in the middle.
3Turn It. It Keeps Its Name.
right anglestill rightacute angleobtuse angle
Turning an angle does not change its name.
Read the opening, not the tilt.
4Parallel and Perpendicular
parallelperpendicular
Parallel lines hold one direction at any length.
Perpendicular lines make a square corner at any tilt.