##
* *Reflection: Developing a Conceptual Understanding
2D Shapes on 3D Shapes - Section 1: Activating Strategy

By starting this lesson in allowing the students to press 3D shapes into play-doh, it really allowed them to conceptualize the various 2D shapes that are on 3D shapes. This proved to be a great activating strategy, and one that helped them to understand the concept of the standard and successfully master it. By allowing them to press the 3D shapes into play-doh, it also helped them to use tools to solve math problems (MP5)

*Math Tools*

*Developing a Conceptual Understanding: Math Tools*

# 2D Shapes on 3D Shapes

Lesson 5 of 18

## Objective: SWBAT identify the two-dimensional shapes that make up the faces of three-dimensional shapes.

#### Activating Strategy

*10 min*

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.

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#### Teaching Strategies

*15 min*

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.

**How many flat surfaces does a cone have?**(1 flat surface)**How can you trace around the flat surface?**(I put the flat surface down on the paper, and then I draw around where the shape meets the paper.)**What other kind of surface does a cone have?**(a curved surface)

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.

**How are the shapes you drew alike? How are they different?**(They all have four sides. The rectangles are not all the same size.)

#### Resources

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#### Independent Practice

*30 min*

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.

#### Resources

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#### Closing/Summarizing

*5 min*

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.

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- LESSON 1: Three Dimensional Shapes
- LESSON 2: Combine 3D Shapes
- LESSON 3: Make New 3D Shapes
- LESSON 4: Take Apart 3D Shapes
- LESSON 5: 2D Shapes on 3D Shapes
- LESSON 6: Sorting 3D Shapes
- LESSON 7: 3D Shapes Unit Assessment
- LESSON 8: Straw Shapes
- LESSON 9: Sort 2D Shapes
- LESSON 10: Describe 2D Shapes
- LESSON 11: Combine 2D Shapes
- LESSON 12: Combine More 2D Shapes
- LESSON 13: Find Shapes in Shapes
- LESSON 14: Take Apart 2D Shapes
- LESSON 15: Equal Parts
- LESSON 16: Halves
- LESSON 17: Fourths
- LESSON 18: Geometry Assessment