Teachers begin teaching about shapes at an early age, so students can develop an almost intuitive feeling for recognizing the different shapes at higher grade levels. This excitement usually begins with firstgrade geometry when the students draw and label 2D shapes. Some 2D shapes include rectangles, squares, trapezoids, triangles and circles. Students also get to know 3D shapes such as cubes, prisms, cones and cylinders. In higher grades, students will calculate the volume and area of shapes.
Regular Polygons

Regular polygons have three or more sides of equal length. You can't make it into the regular polygon club if you don't meet that requirement. Common examples of these straightsided wonders include triangles, which have three sides; squares, which have four sides; and pentagons, which have five sides. Really, you can have as many sides as you want in a regular polygon, as long as all the sides are of equal length, and all the angles have the same measurement. Students also learn about the special words that refer to regular polygons that have more than four sides, such as a pentagon. Other shapes include hexagon, heptagon, octagon, nonagon and decagon  shapes that have six, seven, eight, nine and 10 sides, respectively.
Irregular Polygons

Polygons that don't have equal sides and angles are called irregular polygons. They often look a bit odd and can be difficult to use when you are trying to figure out their area. One example of an irregular polygon is a rectangle. Unlike a regular polygon – like a square that has four sides of equal length  a rectangle has two sets of sides that are of equal length, instead of one set of four sides of equal length. The four angles of a rectangle all have the same measurements, but its four sides are not of equal length.
Curved Shapes

Circles fall into the category of curved shapes; curved shapes are not polygons. An ellipse  which looks a bit like a squashed circle  is similar to a circle and it also is not a polygon. In a circle, the distance from the circle's center to any point on the outside of the circle is the same  no matter where you are on the outside of the circle. In an ellipse, there are two points along the center of the ellipse that are called foci, which means the focal point. The distance between the two foci to the outside of the ellipse always remains the same  no matter where you move the foci.
3D Shapes

Cylinders, cones, cubes, pyramids and prisms are some of the more common 3D shapes. Meanwhile, mathematicians often come up with unique combinations to describe objects in nature. For example, Earth's shape is an oblate spheroid. The term "oblate' refers to the shape's oblong appearance and the word "spheroid" refers to the fact that this shape looks like a notquite perfect sphere. In other words, the Earth has a spherelike shape.
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