Vertex Opens Up

I'm Vertex, made of two straight arms that meet at a single spot, Open them wide or squeeze them tight, and I show you what I've got. Close them tight and barely peek, a narrow little squeeze, Open wide, the gap grows huge, spreading like a breeze.

Right angle, square and steady, like a window's corner true, Acute angle, small and narrow, tighter than that view, Obtuse angle, wide and lazy, opened past the square, Ninety degrees, or less, or more, every angle's there.

A slice of pizza, cut real thin, points sharp and small, A door swung wide against the wall, opened past it all, A ramp that tilts up toward the sky, wider than a square, Every corner in your house has an angle waiting there.

Right angle, square and steady, like a window's corner true, Acute angle, small and narrow, tighter than that view, Obtuse angle, wide and lazy, opened past the square, Ninety degrees, or less, or more, every angle's there.

I only care how far apart my two straight arms have spread, Not how long they stretch or reach, only the gap ahead. Spot a V, a slice, a ramp, a corner in the light, Vertex opens wide or squeezes narrow, tight.

---

Key Concepts: An angle measures how far two lines have opened apart from a shared point, the vertex, not how long the lines are | Angles are measured in degrees, with a full turn equal to three hundred sixty degrees | Right angles measure exactly ninety degrees, acute angles measure less than that, and obtuse angles measure more

Characters: Vertex

Key Words: angle, degree, vertex, right angle, acute, obtuse

Archetypal simplification: Real geometry includes reflex angles, angle pairs, and formal proofs well beyond this age range. The song keeps the true core idea, an angle measures an opening in degrees, and right, acute, and obtuse are three concrete amounts of that opening, at an age-appropriate level.