Without the basic vocabulary of geometry, it is impossible for students to solve geometric problems. Accordingly, third grade students need to understand the concept of circles, squares, rectangles, cylinders, cubes, triangles and other geometric shapes. Introduce one or two geometric shapes at a time. First, provide the students with a brief description of the shape, including its basic properties, such as number of sides and corners. Then, offer the students its nonlinguistic representation, for example, an image or a model. After the students are familiar with the concept, ask them to draw their own examples of the shape -- for example a triangle of a different size or color. Continue this learning pattern until you cover all basic geometric shapes.
Provide students with a number of different objects that have the form of geometric shapes, including triangles, circles and rectangles. Ask students to classify the objects by the shapes they know. This lesson will teach students how to recognize geometric shapes. You can also ask the students to provide their own examples of objects of geometric shapes from their everyday lives.
Ask your students to find similarities between shapes. For example, a square is similar to a rectangle because it has the same number of sides (four) and all the angles are square. Also, help students identify the differences between geometric shapes. After they are fairly comfortable with recognizing the differences and similarities, draw on your whiteboard two geometric shapes, either the same or different. For example, you can draw two different triangles -- the students should be able to identify that both objects are similar because they are still triangles.
Symmetry is an advanced property of shapes. The two shapes are said to be symmetrical if one shape is the exact reflection of another shape, located on the opposite side of the dividing line. Show the kids examples of this concept. After they understand the topic, ask children to come up with examples of symmetry from their everyday lives -- for example, a person's two hands are usually symmetrical.