# 3rd Grade - Cubes, Prisms And Other Objects

 Grade Level: 3rd Skill: Shapes and Geometry Topic: Cubes, Prisms and Other Objects Goal: Identify, describe, and classify common three-dimensional geometric objects (e.g., cube, rectangular solid, sphere, prism, pyramid, cone, cylinder). Skill Description: Measurement and Geometry: 3-d objects (cube, rectangular solid, sphere, prism, pyramid, cone, cylinder) The ability to use a mathematically-correct name when Identifying solid geometrical shapes.

### Sample Problems

 (1) What shape has five faces, five vertices (corners) and 8 edges? (pyramid) (2) What shape has 6 faces, 8 vertices and 12 edges? (cube) (3) Look around the room. Find a shape with one curved face and one flat face, which is a circle. What is it? (cone) (4) What has 6 flat faces (2 squares/4 rectangles), 12 straight edges and 8 corners? (rectangular solid) (5) What figure has one curved face and 2 flat circular faces? (cylinder)

### Learning Tips

 (1) Children can identify objects that can stack and others that can be rolled. Children can identify flat surfaces and corners on objects, as well as faces and edges. (2) Goal: Give children opportunities to identify by name common geometric solids. The purpose of this activity is to provide practice in this skill, so encourage mathematical language. Do not accept terms such as “this one” or “it” when playing this game. Find small items that represent each of these: cube, rectangular solid, sphere, prism, pyramid, cone, and cylinder. Block sets, kitchen drawers, and hardware/tool “catch-all” drawers in your home are good sources to check when looking for these items. Put a few of the items in a basket or box and allow children to draw one out, eyes closed. The child should try to identify the chosen item by touch and feel. When the child has guessed correctly another child can have a turn. Increase complexity by placing more items into the box. (3) (The goal above applies here, too.) Using items from the activity above (Learning Tip 2) place items on a tray or box lid. Allow children to look at the items, and their arrangement on the tray for a given number of seconds—10 or so is a good place to start. While the children are not looking remove one item. Ask children to name the missing item. A variation is to exchange the places of two items and challenge children to recognize the change. (4) Use an old catalog (household items or toys will work best) and allow children to cut out items that contain the geometric solids (: cube, rectangular solid, sphere, prism, pyramid, cone, and cylinder). They might then cut free the parts of the items they found that are just one of the geometric solids and recombine the pieces to “invent” new toys or household objects, giving them fanciful names and uses. Paper and glue can be provided so that the combined shapes are easily displayed without falling apart. (5) Ask, “Are the geometric solids we’ve been studying used to make big items such as buildings, large machinery, vehicles, etc. in our community?” Ask children to enumerate what they see when driving or walking around your neighborhood or town.

### Online Resources

 (1) (2) (3) (4) (5)

### Extra Help Problems

 (1) This is an introductory unit designed to help children recognize and find uses for common geometric solids. Extra help is best provided by allowing extra practice in actually holding, looking at, naming, and finding uses for these items as described in the Learning Tips and by playing the games that accompany this lesson. A flat paper worksheet cannot provide the experiential learning required for expanding experiences with three-dimensional objects. If a worksheet must be included, I would suggest presenting illustrations of the following shapes and asking the child to identify them and state some of their attributes: cube, rectangular solid, sphere, prism, pyramid, cone, cylinder. On another page, illustrations can be similar, but clues can be given such as, “this 3D shape has 6 flat square faces, 12 straight edges and 8 corners.” (cube) The child must write the correct 3D shape next to the picture. A word bank can be included to simplify the worksheet. For an advanced version, the child can draw the shapes and indicate how many edges, faces, and vertices for each shape. I do not have the graphics capabilities to make these shapes and include them.