I start this lesson by handing out 3D shapes and play-doh to each student, or pairs of students. I review which shapes have flat surfaces. I instruct the students to press the flat surface of their 3D shapes into their play-doh. We have a class discussion about the different types of 2D shapes that are made using 3D shapes.
Warning: this is a very fun, tactile, and (potentially messy) activity! I make sure to warn students ahead of time that any silliness with the play-doh will result in, you guessed it, no more play-doh.
For the standard G.A1, I have found that some students may have difficulty recognizing the two-dimensional shape on the three-dimensional shapes. To help overcome this, students press the flat surface of their 3D shape into the play-doh. This allows for them to see the 2D shape that makes up our 3D shapes. Thus, the activity makes the abstract visualization more concrete.
Then using models of 3D shapes, I instruct students to look at their cone. I read the following problem aloud:
Lee places a cone on a piece of paper and draws around its flat surface. What shape did Lee draw?
Then I have children hold a cone and turn it around in different ways to observe its surfaces. Make sure all children have a chance to hold and turn the cone.
I then display the first on the 2D shapes on 3D shapes.ppt. I work through the model with children and make sure they understand that the six rectangles represent the six flat surfaces of the rectangular prism. I have children trace around each side.
Students complete a 2D shapes on 3D shapes_worksheet.docx for the independent portion of this lesson. I work through the first question (slide 2) with the students prior to letting them work independently.
To close out the lesson, I have students write in their journals to tell me which 2D shape is found on the following: cube, cone, cylinder, and rectangular prism.