BACKGROUND:
Students need to learn the skills
involved in describing the world around them. Some descriptions can be
quantitative such as weight and measurement. Other descriptions are
qualitative such as texture, color, and odor. In this exercise
students will begin to describe an object quantitatively. They will
learn to use a metric ruler to measure certain twodimensional
objects. They will see the difference between seeing something as
"big" or "little" and seeing that the object has a
definite measurements.
We highly suggest that you use metric
rulers, especially for science. The international standard is metric
in science, so it is just learning the tools of the trade. You can
still use English, but the more you use metric independent of the
English system, the children will become familiar with the scale.
Conversion is not necessary if a child
has a "feel" for a centimeter, a meter, or a kilometer
independent of an inch, a yard stick, or a mile.
PROCEDURE:
 Inform the students that they
will be learning how scientists describe things. Scientists use the
same methods you would to describe an object to another person.
However, scientists can observe and describe in greater detail because
they are trained.
 Review basic descriptive words such
as colors, shapes, sizes, textures, and other descriptive terms. Hold
up objects like apples, erasers, or pencils, and have the class
describe them. Tell them a Martian has arrived from outer space and he
does not know what the items look like or feel like. Ask the students
how they would describe the object so that the Martian would
understand what it is ?
 Pick a student to come to the front
of the class. (Be sure to pick a student who is not sensitive.) Ask
the students to describe him/her. Try to get them to use words dealing
with size. Tell them that the words "big" and
"little" sometimes do not give all the information we want.
We need to measure them to be accurate. You may want to have the class
compare the student with yourself or another student. Ask the
question, "How much bigger is one person from the other?"
 How do we measure? Give students a
ruler and have them look at centimeters and millimeters.
 Show students different objects and
ask them to predict how large they are. At the beginning they will not
have a clue. After the students have given their answers, measure and
tell the class. After about 5 or 6 of these measurements they may be
able to predict a little better. You are increasing their
observational skills by giving them knowledge to help them predict
more accurately.
 Measure different units in the
doorway so the children can begin to estimate how tall a person is
when they come through the door. In many areas, stores have the door
marked. In case of a robbery, a person would be able to tell how tall
the robber was.
 Pass out the worksheet. The
worksheet helps students measure twodimensional objects. Inform the
students that they will be measuring in the metric system. It is very
easy to measure exactly using the metric system. Model how to measure
the first object on the worksheet. Tell them cm = centimeter and mm =
millimeter. Ask the students to write the large number first (before
the letters cm.) and then count the number of little lines between the
big numbers. We call these little lines "ticks". Each tick
represents one mm. Ask the students to record their answers in the
spaces below the pictures.
