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Teaching Guide
produced by : Sheri L. Johnson
Web Institute for Teachers, Summer, 2000
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Introduction This lesson is an exciting plan
to guide students to use the appropriate formulas to solve for the radius
and diameter of a circle. The hands on activities, measuring, drawing,
identifying and comparing will give students further practice insuring
their success on the standardized test. The student pages reflect
the tasks to be done and the children sending the results to the teacher
on the computer. Students will learn geometry language and use it
to describe objects that they draw.
Aim:This lesson is designed to give 6-8th grade students
a hands on learning activity to solve problems finding the diameter and
radius of a circle and using "pi"in the appropriate formulas.
Rationale Success is important to students
and teachers. Students should learn that geometry is not an
isolated subject. It has a relationship not only in math, but in
art, architecture, engineering, construction, and everyday life. This lesson
is an innovative way to have students engaged in learning and practicing
meaningful activities which will reflect in their success on standardized
tests.
Goals and Objectives: 1. Students will
be able to use different instruments to measure a variety of circular objects
in mm and inches. 2. Draw circles by measuring the diameter
and radius. 3. Find the radius when given the diameter and, find
the diameter when given the radius using the proper formulas. 4.
Observe buildings to discover circular shapes; 5. Define
geometrical terms; 6. Shade a word find in the geometry puzzle.
Audience grades 6-8
Prerequisites: multiplication facts;
division facts; student should be able to read grade appropriate
level; be able to use measuring tools accurately; be able to compare and
contrast circles
Subject-MatterMath-geometry
Instructional Plan Students will work in groups
of five or six(teacher discretion) Each group will be given
seven circular objects(do this before class). They will measure
the diameter of each object. Allow students to volunteer for
the different jobs needed in each group You will need a "gofor",
two artists, one reporter, one typist, one recorder.
One person will record the measurements in mm and in. after they have measured
the diameter of each circular object. The artist(s) will use a compass
and a protractor to draw the objects with accuracy on paper. Each group
will post their finished drawings around the room, after sharing their
findings with the class. A discussion should take place as to whose
findings are correct and show or tell why. The teacher will then
give the correct answers to all groups. The teacher will write on
the chalkboard the terms pi, circle. circumference, diameter, radius.
circle on the board. Explain to the students that you are going
to draw a straight line, and a half line on the board. Have
all students to do the same on their paper. Using a compass,
construct a circle by connecting an arch from one point to the other on
top and on the bottom so that both halves make a circle. Label this
line diameter. Draw a half line with a point in the beginning. This
line will be labeled radius so make sure that it is half of the diameter.
Construct a circle using the formula R=1/2 x D. STUDENTS
SHOULD NOW DO STUDENT
ACTIVITY ONE.
Next have students to draw
two circles . One of the circles should be drawn free hand.
The other circle should be constructed from a radius by using a ruler
or a protractor. They may choose the length, but the measurement
must be in centimeters. At the beginning of the line place a small
point or dot should. Tell students that if the Diameter is two times larger
than the radius then they can use the following formula to solve
for the diameter: D=2 x R. Practice on the board.
Have students to share their results and evaluation with the class.
making sure computation and use of formulas are correct. Do
Student activity 2.
Next ask students to find the perimeter
or distance around a circle by using a string of at least a 36 mm
students will measure the circumference of the circle by placing the string
around the circle; Next use a ruler to measure Th. string used to
measure Show the easier way of finding the circumference by using the formula
C = 3.14 x D. 3.14 is the number that is used to represent II (pi).
The circumference is found by multiplying II times the distance.
Students will then find the circumference of several circles applying the
formula for more practice at their seats. Do student activity 3.
Material 36 mm
string for each student
compass for each group
protractor, paper, pencil, chalkboard, ruler, measuring tape, six circular
objects, tag board circles, and the computer
Assessment and Evaluation Students will
compose and write a geometry table showing the relationship between diameter
radius and circumference. Students will write why geometry is important
in our lives. Students will construct a building using geometric
shapes.
Appendices (optional, if needed)
Resources http:teachervision.com
Glossary
geometry, pi, circle, radius, diameter, and circumference
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