Geometry in straight lines. Key words - line segment, starting and end points, ray, perpendicular & symbol, parallel lines & symbol, angles and classifications - arms, vertex, arc, acute, right angle, obtuse, straight, reflex, complete angle revolution, or angle of 360 degrees, measuring angles, constructing angles, polygon, scalene, isosceles & equilateral triangles, constructing quadrilaterals, squares & rectangles, parallelogram, rhombus & kite, features of a circle - center, circu