Texas TEKS Standards
TX.111.16. Mathematics, Grade 4.
(4.8) Geometry and spatial reasoning. The student identifies and describes attributes of geometric figures using formal geometric language. The student is expected to:
4.8 (A) Identify and describe right, acute, and obtuse angles.
4.8 (B) Identify and describe parallel and intersecting (including perpendicular) lines using concrete objects and pictorial models.