BACKGROUND:
Students should have an understanding of basic
arithmetic skills by the third grade. However, much of their
understanding of arithmetic is how to manipulate numbers and find
answers. Many students find this boring and tedious and develop a
dislike for mathematics. Mathematics is a diverse topic that has
fascinated humans for a long time. Importantly, mathematics is useful
to scientists, business, painters, builders, and economist to name of
few.
Math provides a greater ability to describe objects. If a student has
a good knowledge of geometry, they are able to describe what they see.
Geometry can be divided into linear geometry which describes 1 or 2
dimensional objects, and solid geometry which describes threedimensional
objects. Many subjects in science require this qualitative ability to
describe things. Without the ability to measure or see shapes, a student
will not be able to further their investigations.
In this activity, students describe and measure the length of 2 dimensional
shapes. In the lab, students will be asked to describe different
objects. It is difficult for students to describe shapes and to
estimate length without prior practice. Students will use the
worksheet to help them develop measurement skills and shape recognition.
PROCEDURE:
 Discuss the
differences between 2 dimensional and 3 dimensional objects. Some
shapes such as diamonds or hearts can be both 3 dimensional or 2 dimensional.
Ask the students to describe shapes in the room and estimate linear measurements.
 Describe length of an object
as the longest measurement, width as the shortest. It doesn't matter
which way you turn the object, the measurements are constant. There
are some exceptions to this, especially with objects you cannot move.
Vertical blinds for a window are one exception; the width is always parallel
to the floor and the length is perpendicular to the floor.
 Distribute the worksheets
and metric rulers to the students. Tell the students that they will be
measuring objects using the metric system. They will measure the
objects in centimeters. Using centimeters is much easier to
measure objects and helps students understand decimals and percentage.
For instance, if an object is 1 cm and 5 mm in length, the student writes
1.5 cm. 1 is the number of cm (before the decimal) and 5 is the number
of mm (after the decimal). There is no conversion in metric because
it is base 10 already. Make sure the students know the difference
between cm and mm "ticks" on the ruler. Do not make student “convert”
from the English to metric. They need to get an feeling for the metric
with a conversion factor.
 Model how to do the
first object. On the board write down the width, length, and shape
of the object. Work this problem with the students. Show
the students where to record their answers.
 Allow students time
to complete the worksheet on their own or with a partner. Monitor
them as they work.
 After the students have
finished measuring all the objects, orally review their results.
Give them the names of the shapes if they did not get them correct.
Remember there is margin of error when measuring, so allow them a
little leeway.
