```"The Surface Area of a Cylinder" (Version 2.0)Edwina R. Justice              Gunsaulus Scholastic Academy                               4420 South Sacramento Ave.                               Chicago IL   60632                               (312) 535-7215Introductory Comments:

This is a description of a phenomenological approach presentation.  It is an
extension of a mini-teach, "The Area of a Circle" (1986) and a PA, "The Surface Area
of a Cylinder" (1988).  A problem-solving situation, which requires the use of the
two concepts, was formulated.

Objectives:

1) Use a phenomenological approach to problem-solving.
2) Apply concepts to problem-solving situation.
3) Participate in group activity.

Materials:

Measuring tapes
Round container lids (different circumferences)
Paper circles (equal circumferences)
Construction paper
Rectangles with different dimensions (measure of base should be equal to measure of
circumference of a corresponding lid)

Worksheet:
Cut two circles with equal diameters and one rectangle from cm. grid paper.
Measure of base of rectangle should correspond to measure of circumference of one
circle.  These figures should be used to make a worksheet which can be distributed to
each student.

Recommended Strategy:

Form small groups and measure circumference and diameter of several lids.

Divide circumference by diameter for each lid.

Discuss constant (pi) that results when circumference is divided by diameter.

Use paper circles to show A = pi(r2). (This procedure is explained in SMILE, 1986.) Calculate areas of figures on worksheet.Cut figures and make a cylinder.Relate areas of plane figures to surface area of resulting cylinder. Use rectangles and lids to make several other cylinders.Calculate the surface areas of the cylinders (Use area of each rectangle plus two    times area of corresponding lid). Discuss related equations:   Area of rectangle section of cylinder = base * height                                                 or                                 circumference of lid * height                           Circumference = pi(d)                                         = 2(pi)r                                Diameter = 2r                                Diameter = c/piDevelop formula for surface area of cylinder:                         Area = (2(pi)r2) + (2(pi)rh)Review use of 2 as a constant in equation:      2(pi)r2   (two represents two circles)      2(pi)rh    (two represents two radii or one diameter) Solve problem:        Two rectangular sheets 20 cm. by 24 cm. and 15 cm. by 30 cm. are to be rolled to form cylinders.  What is the height and diameter of the cylinder with maximum surface area that can be formed using either of these sheets? Construct the cylinder with maximum surface area (with lids).Report results to class.```