Video narration
On your notebook page, how can a few strokes behave so differently? A line has no endpoint; with your ruler, it continues forever in both directions. Two lines meeting at one point are intersecting lines. If they meet at exactly ninety degrees, they are perpendicular lines-a right-angle crossing. Now draw two lines that stay the same distance apart. They never meet. These are parallel lines. Here's the turn: draw another line across both. This transversal creates eight angles. At each crossing, angles in matching positions are corresponding angles. Between the parallel lines, angles on opposite sides of the transversal are alternate interior angles. Two adjacent angles whose other sides form a line make a linear pair. So, what do the strokes show? Lines can cross, meet at ninety degrees, or stay apart forever-and one transversal connects them in an angle pattern on your notebook page.