BACKGROUND:
A child’s world before
school is usually threedimensional. 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 threedimensional
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 humanmade. 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 twodimensional 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.
