The perimeter of a rectangular yard is 200 feet. The measure of its width is 40 feet.

Step A

What is the length, in feet, of its length?

Step B

Use what you know about perimeter to explain how you determined the length. Use words, numbers, and/or symbols in your explanation.

Use what you know about perimeter to explain why the length you determined is correct. Use words, numbers, and/or symbols in your explanation.

Step A is scored 0 (Incorrect) or 1 (Correct) and assesses 3.C.1.d.
Step B is scored with a 3 point (0, 1, 2) rubric and assesses Processes of Mathematics.

Step A Answer: 60

Step B Sample correct response:

How: Perimeter is the distance around a figure. So for a rectangle, the perimeter is the sum of the width plus the width plus the length plus the length. Since the opposite sides of a rectangle have the same length, the perimeter is w + w + l + l, or 2 (w) + 2 (l) = 200. If I substitute 40 for w, then I get

Why: The perimeter of a rectangle is 2 (w) +2 (l). The perimeter of this rectangle is 200 feet. When I substitute 60 into the equation, it makes it true.

So the length must be 60 feet.

Score 2

The response demonstrates a complete understanding and analysis of a problem.

• Application of a reasonable strategy in the context of the problem is indicated.
• Explanation¹ of and/or justification² for the mathematical process(es) used to solve a problem is clear, developed, and logical.
• Connections and/or extensions made within mathematics or outside of mathematics are clear.
• Supportive information and/or numbers are provided as appropriate. ³

Score 1

The response demonstrates a minimal understanding and analysis of a problem.

• Partial application of a strategy in the context of the problem is indicated.
• Explanation¹ of and/or justification² for the mathematical process(es) used to solve a problem is partially developed, logically flawed, or missing.
• Connections and/or extensions made within mathematics or outside of mathematics are partial or overly general, or flawed.
• Supportive information and/or numbers may or may not be provided as appropriate.³

Score 0

The response is completely incorrect, irrelevant to the problem, or missing.⁴

Note 1:

Explanation refers to students' ability to communicate how they arrived at the solution for an item using the language of mathematics.

Note 2:

Justification refers to students' ability to support the reasoning used to solve a problem, or to demonstrate why the solution is correct using mathematical concepts and principles.

Note 3:

Students need to complete rubric criteria for explanation, justification, connections and/or extensions as cued for in a given problem.

Note 4:

Merely an exact copy or paraphrase of the problem will receive a score of "0".

Rubric Document Date: August 2003