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Topic: Estimating
Area of Irregular Objects
NCSCS: Sixth Grade
Mathematics Objectives: 2.12 Estimate solutions to problems
involving geometry and measurement. Determine when estimates are sufficient
for the measurement situation. 2.13 Analyze problem situations, select
appropriate strategies, and use an organized approach to solve non-routine
and increasingly complex problems involving geometry and measurement.
Use technology as appropriate.
Interdisciplinary
Connection:
Technology/Reading/Writing
Differentiation/Accommodation/Student
Voice/Choice:
Differentiation /Accommodation - Small groups - Put six types of trees
on the board, let students chose a tree. Only four students to a tree.
Student Voice/Choice - Students may choose any four color combination
for marking and counting square inches. Students also have a choice of
using a calculator.
Materials
- Six - irregular
figures
- See-through square
inch color tiles
- Overhead projector
- Four overheads
of irregular figures
- Scoresheets
(One for each student)
- Calculator
- Six large maps
(maps to scale)of Joyce Kilmer Memorial Forest
- 1 square inch
is equal to 1 acre (1 sq. in = 100 acres)
- Twenty-five brochures
of Joyce Kilmer Memorial Forest
Procedures:
- Area is the number
of square units needed to cover the surface of a figure. To find area,
one can count the number of square units inside the figure.
- The teacher will
demonstrate how to count square units by using the overhead projector.
- The teacher will
place an irregular figure on the overhead.
- The teacher will
use four different colors of clear square inch color tiles to count
the area of the figure's surface.
- Full squares
will be red
- Almost full
squares will be blue
- Half-full square
will be yellow
- Less than half-full
will be green
- Full squares
will be counted as 1
- Almost full
squares will be counted as 1
- Half-full squares
will be counted as one-half or .5
- Squares that
are less than half-full will not be counted
- The teacher will
demonstrate how to place the squares by starting in the center and working
to the outer edges of the figure. Center squares will be red and as
one works toward edges, squares will be place by almost full - blue,
half-full - yellow, and less full - green.
- When all the surface
area is covered the teacher counts tiles and adds their values.
- Example:
- 8 red squares
will receive the value of 8.
- 10 almost full
squares will receive the value of 10.
- 13 half-full
will receive the value of 6 and one-half or 6.5.
- 6 less than
half full will not be counted.
- The total
surface area of the irregular figure is equal to 30.5 square
inches, this figure will be rounded-off to 31 square inches.
- As a guided practice
students will work three more irregular figures. When all students are
through the teacher will work the figures on the overhead and students
will check their estimations.
- Students will work
six irregular figures on their own and record their results.
- When all students
are through, students will be placed in their groups and be given a
map of Joyce Kilmer Memorial Forest.
- Students will find
the area of Joyce Kilmer Memorial Forest.
- Students will record
their tiles on scoresheet.
- Students will assign
values to tiles and calculate total area of Joyce Kilmer Memorial Forest.
The total area of the map should be equal to 380 square inches, which
is equal to 3,800 square acres.
- The teacher will
give each student a Joyce Kilmer Memorial Forest brochure which was
donated to the class by Cheoah Ranger District. For a brochure write
Cheoah Ranger District, Route 1, Box 16-A, Robbinsville, N. C. 28771.
- The teacher will
ask each student to read the brochure and at the bottom of their scoresheet
write a descriptive writing of Joyce Kilmer Memorial Forest using the
brochure and information they have collected from previous lessons.
Timeframe for Lesson:
- Two 50 minutes
class periods
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Page Author: Bobbie Burchfield
10/13/02
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