Children construct and use angle testers using folded paper, and using chenille sticks and straws.
They identify angles with 2 lines as the relative slant between 2 arms that meet at a vertex.
They identify angles with 1 line as the amount of turn around a vertex.
They use angle testers to test angles with 2 lines, for example, angles in buildings.
They use angle testers to test angles with 1 line, for example, door opening, clock hand movement.
They use angle testers to identify angles that are right angles, obtuse angles and acute angles.