Vocabulary:
 acute angle
 angle
 area
 congruent
 degree
 geometry
 intersecting lines
 isosceles
 length
 obtuse angle
 parallel lines
 parallelogram
 perimeter
 plane
 point
 polygon.
 puzzle
 quadrilateral
 ray
 rectangle
 right angle
 rotate
 shapes
 similarity
 square
 symmetry
 tangram
 triangle
 unit
 vertex
 width