AI Tutor
Grab a pair of scissors and open them just a tiny bit, then halfway like a book corner, then wide open like a fan.
Every time you open those blades, you create an angle, which is simply the amount of turn between two lines meeting at a point.
Triangles have three corners, and the size of those corners gives each triangle its official family name.
Before we sort triangles, what are the three angle types we look for?

The Three Angle Types

A right angle makes a perfect square corner, measuring exactly 90∘90^\circ like the corner of a sheet of paper.
An acute angle is sharp and narrow, measuring less than 90∘90^\circ (think of a sharp pencil tip or a cute little kitten).
An obtuse angle opens wide, measuring greater than 90∘90^\circ and less than 180∘180^\circ.
Now, how do these three angle shapes name our triangles?

The Three Triangle Families

An acute triangle has three acute angles — every single inside corner must be smaller than 90∘90^\circ.
A right triangle has exactly one right angle (90∘90^\circ), usually marked with a tiny square box in the corner.