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Goal 2 Geometry, Measurement, And Reasoning

Expectation 2.1 The student will represent and analyze two- and three-dimensional figures using tools and technology when appropriate.

Indicator 2.1.3 The student will use transformations to move figures, create designs, and/or demonstrate geometric properties.

Assessment Limits:

  • Transformations include reflections, rotations, translations, and dilations.
  • Items should go beyond the identification of transformations.
  • Essential properties and relationships include the following: congruence, similarity, and symmetry.
  • The student's explanation of a transformation must include the following:
    • translation – distance and direction
    • reflection – line of reflection
    • rotation – center of rotation, angle measure, direction (clockwise or counterclockwise)
    • dilation – center and scale factor
  • Paper folding and the use of MirasTM and mirrors are appropriate methods for performing transformations, and their use must be referenced.

Brief Constructed Response (BCR) Item - Released in 2000

A triangle with vertices at (0, 0), (0, 6), and (4, 0) is shown on the grid below.

Complete the following in the answer box below:
  • Draw the dilation image of the triangle using a scale factor of 3 and using (0, 0) as the center of the dilation on the grid provided in the Answer Book.
     
  • What is the difference between a dilation using a scale factor greater than 1 and a dilation using a scale factor between 0 and 1? Use examples to justify your answer.
     

The following 12 Sample Student Responses represent a range of score points.

Sample Student Response #1

image of student response

Score for Sample Student Response #1: Rubric Score 2

Annotation: This response indicates application of a reasonable strategy that leads to a correct representation that conveys an overall conceptual understanding of the problem. The written explanation does not clearly justify dilation by scale factors greater than 1, and does not address dilation by scale factors between 0 and 1. "...with a scale factor of 3 you can just times everything by 3" seems to explain what he/she did in drawing the dilation image rather than to address the question of explaining dilation by a scale factor. This response demonstrates a conceptual understanding and analysis of the problem. Compare to Anchor Paper #3.


Sample Student Response #2

image of student response

Score for Sample Student Response #2: Rubric Score 1

Annotation: This response indicates application of an inappropriate strategy. The representation is incorrect, but shows some understanding of scaling up in size, although not by the correct factor. The justification supports the solution "...double the amount usually when the scale factor is greater than one." The student does not address a dilation with a scale factor between 0 and 1. The response demonstrates minimal understanding and analysis of the problem.


Sample Student Response #3

image of student response

Score for Sample Student Response #3: Rubric Score 3

Annotation: This response indicates application of a reasonable strategy. The representation is correct. The justification is clearly presented, fully developed and supports the solution, revealing a correct strategy. The student explains the differences in dilation by scale factors between 0 and 1 and scale factors greater than 1 in terms of multiplying by the scale factor, giving specific examples. The student states, "...if the scale factor is 1/2 the coordinates would only be 1/2 of the original" and "If for example the Sf is >1, like it is in the problem above, the coordinates are multiplied by 3 and the figure will be bigger." The response demonstrates a complete understanding and analysis of the problem.


Sample Student Response #4

image of student response

Score for Sample Student Response #4: Rubric Score 1

Annotation: This response indicates application of an inappropriate strategy. The representation is incorrect, but it has some relevance as the student has drawn a larger triangle. The justification, "With a dilation with scale factor between 0 and 1, the figure hardly moves and is basically the same. With a scale factor greater than 1, the figure's movements are very noticeable, and usually very big," has some relevance, but it is undeveloped and does not reveal a correct strategy for dilation. The response demonstrates a minimal understanding and analysis of the problem. Compare to Anchor Paper #2.


Sample Student Response #5

image of student response

Score for Sample Student Response #5: Rubric Score 3

Annotation: This response indicates application of a reasonable strategy. The representation is correct. The justification is clearly presented, fully developed and supports the solution, revealing a correct strategy. The student explains the differences in dilation by scale factors greater than 1 and scale factors between 0 and 1 in terms of multiplying by the scale factor, giving specific examples. ("The dilation of 3 made the triangle 3 times as big" and "… scale factor less then 1 decreases the size of a figure. dilation scale factor = .5 2 • .5=1.") The response demonstrates a complete understanding and analysis of the problem. Compare to Anchor Paper #6.


Sample Student Response #6

image of student response

Score for Sample Student Response #6: Rubric Score 2

Annotation: This response indicates application of a reasonable strategy that leads to a correct representation that conveys an overall conceptual understanding of the problem. The student does not address a dilation with the required scale factor less than 1. Although the student explains, "1 is just a replica. More than 1 would be a larger shape that is proportionate," the student does not justify this statement. This response demonstrates a conceptual understanding and analysis of the problem. Compare to Anchor Paper #4.


Sample Student Response #7

image of student response

Score for Sample Student Response #7: Rubric Score 2

Annotation: This response indicates application of a reasonable strategy that leads to a correct representation that conveys an overall conceptual understanding of the problem. The student does not address a dilation with the required scale factor less than or equal to 1. The student explains, "Since the larger triangle is 3 times as big as the smaller one, the scale factor and dilation is different (larger)." This response demonstrates a conceptual understanding and analysis of the problem. Compare to Anchor Paper #4.


Sample Student Response #8

image of student response

Score for Sample Student Response #8: Rubric Score 1

Annotation: This response indicates application of an inappropriate strategy. The representation is incorrect, but has some relevance as the student has drawn a smaller triangle with a scale factor of 1/3. The justification "the bigger the scale factor the smaller the object is on scale" does not reveal a correct strategy for dilation, but this is consistent with the triangle drawn. The response demonstrates a minimal understanding and analysis of the problem.


Sample Student Response #9

image of student response

Score for Sample Student Response #9: Rubric Score 3

Annotation: This response indicates application of a reasonable strategy. The representation is correct. The justification is clearly presented, fully developed and supports the solution, revealing a correct strategy. The student explains the differences in dilation by scale factors between 0 and 1 and scale factors greater than 1 in terms of multiplying by the scale factor, giving specific examples. ("...a number being multiplied by .5, the number will be reduced in half." and "...if a number is multiplied by 2, then it will double.") The response demonstrates a complete understanding and analysis of the problem. Compare to Anchor Paper #6.


Sample Student Response #10

image of student response

Score for Sample Student Response #10: Rubric Score 1

Annotation: This response indicates application of an inappropriate strategy. The representation is incorrect, but has some relevance as the student has drawn a larger triangle. The student adds three units to two legs of the triangle rather than multiplying by the scale factor of three--an inappropriate strategy. The student's justification, "The dilation of 3 makes it bigger by 3," is consistent with the representation. This response demonstrates a minimal understanding and analysis of the problem. Compare to Anchor Paper #2.


Sample Student Response #11

image of student response

Score for Sample Student Response #11: Rubric Score 3

Annotation: This response indicates application of a reasonable strategy. The representation is correct. The justification is clearly presented, fully developed and supports the solution, revealing a correct strategy. The student explains the differences in dilation by scale factors between 0 and 1 and scale factors greater than 1 in terms of multiplying by the scale factor, giving specific examples. ("...(0,6) becomes (0,3) and (4,0) becomes (2,0) with scale .5." "With scale 3, it became (0,18) and (12,0), calling for a figure 3 times as big." The response demonstrates a complete understanding and analysis of the problem. Compare to Anchor Paper #6.


Sample Student Response #12

image of student response

Score for Sample Student Response #12: Rubric Score 2

Annotation: This response indicates application of a reasonable strategy that leads to a correct representation that conveys an overall conceptual understanding of the problem. The student does not address a dilation with the required scale factor less than or equal to 1. "To make the smaller triangle to grow by the scale factor of 3 is to multiply the numbers by 3. Then draw them on the scale and use a ruler to connect the dots" explains what he/she did in drawing the dilation image rather than clearly addressing the question of explaining dilation by scale factor. This response demonstrates a conceptual understanding and analysis of the problem. Compare to Anchor Paper #3.


Additional Resources

Anchor Papers used in scoring

Brief Constructed Response (BCR) Rubric

Print: Scoring Rubric (pdf)
Score 3

The response indicates application of a reasonable strategy that leads to a correct solution in the context of the problem. The representations are essentially correct. The explanation and/or justification is logically sound, clearly presented, fully developed, supports the solution, and does not contain significant mathematical errors. The response demonstrates a complete understanding and analysis of the problem.

Score 2

The response indicates application of a reasonable strategy that may be incomplete or undeveloped. It may or may not lead to a correct solution. The representations are fundamentally correct. The explanation and/or justification supports the solution and is plausible, although it may not be well developed or complete. The response demonstrates a conceptual understanding and analysis of the problem.

Score 1

The response indicates little or no attempt to apply a reasonable strategy or applies an inappropriate strategy. It may or may not have the correct answer. The representations are incomplete or missing. The explanation and/or justification reveals serious flaws in reasoning. The explanation and/or justification may be incomplete or missing. The response demonstrates a minimal understanding and analysis of the problem.

Score 0

The response is completely incorrect or irrelevant. There may be no response, or the response may state, “I don't know.”

Explanation refers to the student using the language of mathematics to communicate how the student arrived at the solution.

Justification refers to the student using mathematical principles to support the reasoning used to solve the problem or to demonstrate that the solution is correct. This could include the appropriate definitions, postulates and theorems.

Essentially correct representations may contain a few minor errors such as missing labels, reversed axes, or scales that are not uniform.

Fundamentally correct representations may contain several minor errors such as missing labels, reversed axes, or scales that are not uniform.

Last Revised 8/16/00

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Resources for 2.1.3:
Skill Statements | PUBLIC RELEASE ITEMS | Lesson Plans |