2-Dimensional Representations of 3-Dimensional Objects

By Maureen M. Lewicki on Apr 24, 2017

A.   Students will identify the parts of a two dimensional tactile graphic of a rectangular prism.

B.   Students will identify the parts of a three dimensional rectangular prism.

Rationale

Students of the 21 century are daily exposed to 2 dimensional representations of three dimensional objects.  The common core standards include presenting students with two and three dimensional objects.

Use of three dimensional objects is always preferable to the two dimensional representations, but with direct and purposeful instruction, a blind student can access the dimensional representations with understanding. Giving direct and purposeful instruction to a braille reader prepares them for accessing tactile graphics with ease as well as the deeper understanding of what the graphics represent.

Materials

• Rectangular box
• Tactile graphic of a three dimensional image of a rectangular prism

Procedure

1.  Present the student with the rectangular box, and give them time to explore it.   2.  Encourage using both hands to explore the box   3.  Ask them to describe what they notice, leading them in a discussion with some of the following questions:
• What is the shape of the short side of the box?
• What is the shape of the long side of the box?
• What is the shape of the top and bottom of the box?
• Does the shape of the sides change, if you move the box to various positions? If they are unsure, encourage them to turn the box in several ways, and have them examine the sides. This is an important concept, because in the two dimensional graphics the sides of a rectangular prism are parallelograms, because the eye needs the sides to change shape in order to show depth. It is important for them to understand the shape of the rectangular prism, in two dimensions, does NOT change.
• Ask the student if they can feel the inside of the box, and guide them in understanding that they cannot, unless they open the box and put their hands in.
• Explain that neither the eye, nor the hand can see the inside wall of the shape from the outside.
• Demonstrate, and articulate as you are demonstrating, that you are inserting your arm into the hole on the short sides of the box. Explain to the student that you are inserting your arm into the box and reaching to the back of the box, in order to feel the inside walls of the shape.
• Allow the student to do that same, guiding their hand, if necessary to the back of the box, but putting your hand into the box from the opened top.
• Present the student with a crisp, large, tactile graphic of a rectangular prism.
• Allow them time to explore.
• Ask them to describe what they see. (Often a student will notice that the ‘side’ of the rectangle is a parallelogram. They will notice, or guide them in noting:
• That some lines are dotted and some are solid.
• There is a parallelogram on the side and one on top.
• There is more than one rectangle.
• Explain to the student that in order to represent depth to the eye, the rectangle must have a parallelogram on the side, to indicate that the image is three dimensional.
• Explain to the student that the dotted lines indicate parts of the box that ‘exist’ but cannot be seen with the eye.
• Allow the student to move back and forth between the tactile graphic and the three dimension shape to notice differences and similarities.
• Guide them in feeling the back line of the box, from the inside, and then the dotted line on the graphic, which represents the back of the shape.
• Guide them in exploring and comparing the three dimensional shape and the tactile graphic.
• Follow-up
• Repeated presentation of the solid and the graphic will help the student remember what the graphic represents, and will lessen the confusion and frustration of the student when they are presented with these graphics in a classroom
• Introduce other tactile graphics with solid objects, similarly prepared in advance.
* This lesson is for: student totally blind, braille reader, audio learner, advanced academics: however, although a strong braille reader, tactile images pose a very significant challenge. The lesson would also be extremely appropriate for a blind or visually impaired learner, or a learner who has difficulty learning concepts