Lines, Rays & Angles
Draw and identify points, lines, line segments, rays, angles (right, acute, obtuse), and perpendicular and parallel lines; identify these in two-dimensional figures
What a learner can do afterwards
- Draw a pair of perpendicular lines and a pair of parallel lines
- Identify all pairs of parallel sides in a trapezoid
- Mark a right angle, an acute angle, and an obtuse angle in a given figure
The lesson
A point marks one exact spot. It has no size, just a location, and you draw it as a small dot with a label like point A.
A line runs straight and never stops in either direction, so you draw an arrow on both ends. A line segment is part of a line with two endpoints, so it has a fixed length and no arrows. A ray starts at one endpoint and shoots straight in just one direction forever, so it gets one arrow.
Think of a tightly stretched jump rope held at both ends: that is like a line segment, since it stops at two fixed points. Now think of a flashlight beam shining into a dark sky: that is like a ray, since it starts at the flashlight and keeps going in one direction.
Look at the corner where two sides meet in any figure. A square corner is a right angle, a narrower opening is acute, and a wider opening is obtuse.
Points, lines, segments, and rays are the building blocks you use to spot parallel sides, perpendicular corners, and angle types inside any figure.
Watch it
Where it sits
Where this leads
Jobs that lean on this skill. Follow one to see everything it is built on.
8 questions wait behind this lesson, each with its answer explained. Every answer feeds the sky: stars light as they are learned, and dim when it is time to come back.