The first thing students need to learn about three-dimensional shapes is the attributes of these shapes. This includes the number of sides each shape has, the number and type of angles and the different two-dimensional shapes that make up each three-dimensional shape. Examining models of the different shapes can help students learn this skill.
Third graders may enjoy making models of some of the three-dimensional shapes. Use toothpicks or craft sticks along with some way to connect them, such as bits of clay, glue or soft candies like gum drops. Start by making familiar two-dimensional shapes, then add more sides to turn them into less familiar three-dimensional shapes.
Have students work either individually or in small teams to find real life examples of the different three-dimensional shapes. Do this in the classroom as long as you have examples of all the shapes on the list, or assign this as homework. If you do the activity in the classroom, give a small prize to the individual or team that finishes first, or the team that finds the most examples in the time allowed.
Third graders also need to learn about the surface area and volume of the various three-dimensional shapes. Surface area may be easier to understand if you have students make paper models of some of the shapes, using handouts that have the guide showing where to cut, fold and glue to create the shape. Hollow examples of the shapes can be filled with sand, water or another material to help students compare the volumes of different three-dimensional shapes.