2.8.B 2.8.C 2.8.E

A two-dimensional figure is a figure without thickness; it is flat.

A polygon is a two-dimensional figure
made up of non-overlapping, straight line segments.

The point where two line segments meet is a vertex.

Texas Essential Knowledge and Skills (TEKS)

2.8.B

classify and sort three-dimensional solids, including spheres, cones, cylinders, rectangular prisms (including cubes as special rectangular prisms), and triangular prisms, based on attributes using formal geometric language;

2.8.C

classify and sort polygons with 12 or fewer sides according to attributes, including identifying the number of sides and number of vertices;

2.8.E

decompose two-dimensional shapes such as cutting out a square from a rectangle, dividing a shape in half, or partitioning a rectangle into identical triangles and identify the resulting geometric parts.