## Plane Shapes and Fractions

### Identify and Sort Basic Plane Shapes

Children are familiar with plane, or flat, figures in real-world designs and objects such as sheets of paper. They learn to recognize, describe, and compare four basic closed plane figures. The circle is round. It is composed of points in a plane that are the same distance from a given point called the center of the circle. Squares and rectangles have four straight sides and four square corners (vertices). The square is actually a special rectangle in which all four sides are the same length. Triangles have three sides and three corners (vertices). At this grade level, the fact that all squares are rectangles is not taught. Squares and rectangles are taught as independent shapes.

Plane figures have various attributes. They may be large or small. Triangles and rectangles have different numbers of sides. Pictures of geometric shapes may vary in color, too. Using attributes such as size, color, and shape, children may sort plane figures and tell which figures belong or do not belong to a designated set. For example, a given set may have only blue shapes, so a blue triangle belongs; a red circle does not belong. Another set has only triangles, so a square does not belong, and so on.

### Identify Symmetric Figures and Equal Parts

A figure has symmetry if it can be folded so that the two parts match exactly. Some children can visually identify symmetrical shapes; other children may need practice in folding and cutting out shapes and then refolding them to see that the parts match exactly. Children can also examine pictures and classroom objects to see if they have line symmetry or not. Identifying lines of symmetry leads to discovering halves, objects, or drawings with two congruent parts. Most children can relate the concept of finding “half” to sharing something equally with another person.

Finally, children investigate ways to combine and subdivide figures. They cover designated areas with pattern blocks, often finding that there are many ways to accomplish this task.

Teaching Model: Identify and Sort Basic Plane Shapes