Pay attention to two alignments when measuring the angle: the center of the protractor is aligned with the vertex of the angle.

The 0 scale line of the protractor is aligned with one side of the corner.

After the two are aligned, the other side of the angle faces the scale line several times, and this angle is several degrees.

Look at the scale to distinguish the inner and outer rings. Here I'll teach you a little trick:

Distinguish the inner and outer rings, and follow the scale of 0; The scale of 0 in the outer ring depends on the scale of the outer ring.

The scale of 0 in the inner ring depends on the scale of the inner ring. Keep it in mind and never forget it.