# Make New 3D Shapes

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## Objective

SWBAT use composite three-dimensional shapes to build new shapes.

#### Big Idea

Watch out Bob the Builder! In this lesson, students will use 3D shapes to make new 3D shapes.

## Activating Strategy

10 minutes

I start this lesson with the book, “Three Dimensional Shapes: Cones”.  I like to use this book because it demonstrates the various real life uses for 3D shapes.  There are four books in the series: cones, cubes, spheres and cylinders.  All of the books show real life 3D objects that are seen in our everyday lives.

I then give students, or pairs of students, a cube and a cylinder and ask them to combine them to make new shapes.  After allowing some students to share, I ask the class:

• What are the different ways you can combine the two shapes? (I can move the cylinder on top of the cube. I can move the cube on top of the cylinder. I can move the cube next to the cylinder.)
• Can a cone go on top of a cube? Can a cube go on top of a cone? Explain. (A cone goes on top of a cube with the flat surface of the cone on the flat surface of the cube. A cube cannot go on top of a cone.)
• Why would cylinders in a combined shape be standing up and not lying on their sides? (A cylinder has flat surfaces at its ends, so it can stand up. It also has a curved surface, so it can roll on its side.)

For the standard, 1.G.A2, I have found that some students may have difficulty visualizing how to combine the smaller shapes into larger shapes.  To help them visualize the combination, I start with modeling making a shape myself and having the student select the two shapes that I used to copy the new shape.  We then discuss how the shapes that we used are still within the new larger shape that we created.  I repeat the activity.  By allowing the student to select the appropriate shapes that I used, they will begin to visualize the smaller shapes that were used to make the larger shape.

## Teaching Strategies

15 minutes

I then tell students that I’m making a new shape by putting a box on top of another box.  I have students show me with their shapes, what my shape would look like.  Then I display the first slide of the Make new 3D shapes.ppt and ask students if the new 3D shape shown is something that Jeff could have made.  I then guide the discussion:

• Describe the smaller box.  (It is shaped like a cube.)
• Describe the larger box. (It is shaped like a rectangular prism, and it is not a cube.)

Have students copy the shape shown on the slide.  I then display the second slide, and work through the model with children. Encourage them to describe how each tower is made from a cube and a cylinder. Then have children predict which composite shape can be made from the two towers before building it to check.

• Which new shape will you make when you combine your shape with your neighbor's? Why? (I will circle the second shape. The flat surfaces of the cubes and cylinders are still touching.)
• Explain why you cannot make the other shape. (The shapes in the tower in Step 1 are stacked with the flat surfaces matched. The combined shape has a curved surface next to a flat surface.)

A key component to this lesson is to remind students that the new shapes they build cannot move to new positions when they combine.  For example, if the flat surfaces are touching, then they need to remain touching.

I was really focused during this lesson on bringing MP1 into the mix.  I feel that the children were able to use what they learned about combining three-dimensional shapes leading up to this point to create new shapes. Using concrete objects, children explain their reasoning as they identify attributes and the positions of the shapes in the new construction. With experience, children become better at and more confident with identifying characteristics of new shapes that may be created. This comes naturally as they work with models to find which combinations are reasonable and which are not.

## Independent Practice

30 minutes

Then, displaying the third slide, I read the chart with the students.  Before handing out the Make new 3D shapes_worksheet.docx, I also remind them that the shapes they see in the Build and Repeat column cannot move to new positions when they combine.

In this video, the student is explaining his rationale on why the answer he selected was the correct answer.  Since he didn't grasp the vocabulary of the flat surface of the rectangular prism touching the curved surface of the cylinder, I went back and reviewed with him the importance of the surfaces that are touching and how that needs to remain the same.

## Closing/Summarizing

5 minutes

To close out this lesson, I instruct students to use a cube and a cylinder to build a new shape. I then instruct them to draw their new shapes in their math journal.