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RUBRIC

 

 

5 – Must have correct answer, must explain how to get area of circle, rectangle, must show how to subtract to get area of shaded area, must show how to find radius of circle.

 

4- Must have correct answer, must explain how to get area of circle, rectangle.

 

3- A.  Correct answer, shows both areas and subtraction, no explanation.

 

     B. Correct answer showing 2 out of 3 major procedures and some explanation.

 

     C. Incorrect answer, correctly arrived at from one mistake (such as using an incorrect radius.)

 

2-  A. Correct answer with the area of the circles shown and some explanation.

    

      B. Incorrect answer with 2 out of 3 procedures and no explanation.

 

1-  A. Correct answer with no support.

 

      B. Incorrect answer, but one thing done correctly (such as area of the rectangle.

 

0 – Blank or unresponsive paper.

 

SOLUTION:    Area of rectangle – area of 3 circles.

 

Rectangle’s Area = A = L x W

                                A = 19 x 7

                                A= 133  

 

 

Area of 3 circles =        3(Pi x R x R)

              3(Pi x 2.5 x 2.5)

              3(Pi x 6.25)

              3(19.634)

              58.90486225

 

133-58.90486225 = 74.09513775 sq. in         (calc. Pi)

 

or                             74.125 sq. in (using 3.14)

or                             74.07142857 (using 22/7).

 

 

All three answers round to 74

 

 

Note: Radius found  by:    diameter is7- (1+1) or 5.

                                                       R= 1/2 x 5 =2.5

 

 

 

 

 

 

 

(Not drawn to scale)

          The road crew is repainting the metal background of traffic lights. What is the area of the shaded region in square inches, according to the diagram. (Round your answer to the nearest whole number.)

 

 

For full credit you must do the following:

1)      show or describe each step of your work, even if you did it in your head (mental math) or used a calculator.

2)    Write an explanation stating the mathematical reason(s) why you chose each of your steps.

 

 

 Open-Ended Template

 

Names:

       By Robert Donnelly, Curt Snelbaker, Sandra Madden, and Marcia Curry.

 

Grade Level: 7/8

 

Content Area: Geometry (area)

 

PA standard(s) addresses: Standard: 2.3.8A

 

NCTM standard(s) addressed: Grade 6-8 Measurement

 

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