Practice angles: classify them as acute, right, or obtuse, and find missing angles using complementary, supplementary, vertical, and triangle-sum relationships.
An acute angle is less than 90°, a right angle is exactly 90°, and an obtuse angle is more than 90° (but less than 180°).
Complementary angles add up to 90°; supplementary angles add up to 180°. If one supplementary angle is 115°, the other is 180 − 115 = 65°.
Cubles kits are geometry in your hands: nets, faces, edges and vertices that fold and click into a poseable 3D character. No scissors, no glue, about 15 minutes.
