3rd Grade Math Lessons: Understanding Shapes

Which Shapes Should My 3rd Grader Know?

Make sure your child is prepared for future math classes by practicing shape classifications at home. Ultimately, your 3rd grader should be able to classify shapes into categories, such as quadrilaterals, rhombuses and rectangles. The properties defining certain shapes may also be addressed at this level. For example, all squares are rectangles, but not all rectangles are squares. Both squares and rectangles are quadrilaterals. In addition, all four sides of a square are the same length and the opposite sides of rectangles are the same length.

In 3rd grade, students also learn how to find the perimeter and area of shapes. They don't usually use math formulas at this level. Instead, the shapes may be drawn on graph paper and the students count units. When you review this information with your child, provide him or her with graph paper to aid visualization.

Shape Practice

Classification

To help your child learn how to classify shapes, make it into a game. Look for shapes everywhere you go, like stop signs (octagons) or speed limit signs (rectangles). A kite with equal sides can be an example of a rhombus and many buildings are shaped like rectangles. Around the house, you'll probably find trapezoids (lamp shades) and squares (picture frames).

Perimeter

Perimeter worksheets can provide your 3rd grader with practice; however, it's easy to incorporate perimeter into everyday activities. For instance, your child may measure the perimeter of the dinner table or of an entire room. The benefit of real-world application is that your child will use measuring skills in addition to practicing how to calculate perimeter. For a challenge, ask your child to find the perimeter of unusual shapes, like triangles or anything around the house that has flat sides.

Area

Like perimeter, area is often used in real life, such as when you're replacing the rug in your child's room or buying new furniture. Use opportunities like this to invite your child to help. For a room that's 18 feet by 12 feet, the area would be 216 square feet because 18 x 12 = 216. Alternatively, if you want to make a worksheet for your child, consider making it on graph paper. This way, your child can visualize the area and count the rows and columns of squares that fit inside of the shape.