BACKGROUND:
A child’s world before
school is usually three-dimensional. Most things they see and touch
has height, depth, width, and weight. When they arrive at school,
a curious thing happens. Students are asked to draw or write on a
flat, 2 dimensional piece of paper. It is difficult for students
to draw depth of objects, so they usually draw a circle for a sphere, a
square for a box, or a triangle for a cone.
Descriptions in science rely
on three dimensions. Objects are spheres, not circles. It is
important for teachers to provide vocabulary for the three-dimensional
world. Students can then describe accurately what they are seeing.
PROCEDURE:
- Review two
dimensional and three dimensional shapes by using the worksheet.
Have the students color each of the shapes. Discuss the differences between
two and three dimensional objects.
- With the worksheet
as a guide, identify different shapes in the classroom. Then go outside
and continue to identify shapes. Students may notice that there are
more geometric shapes when objects are human-made. Nature tends to
be more obscure in their geometry.
- Inside the classroom,
circles can be represented by wheels on toys. Spheres can be represented
by balls or globes. Notice that many objects are not perfectly geometric.
A desk is a rhombohedral shape (a 3 dimensional rectangular).
- Outside the classroom,
finding objects is more difficult. A blade of grass is rectangular,
but it has depth to it! If you look at the top of a slab of cement,
it appears two-dimensional yet it also has depth to it. Trees can
be columns or pillars. Wheels on cars are circular. Many objects
are not strictly geometric structures, but a series of curves. Describing
curved objects is difficult and actually is the mathematical basis of many
fields of calculus.
- Encourage students to
draw their favorite shape on the worksheet.
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