what does the transformations- based focus of the common core state standards mean? nanette seago...
TRANSCRIPT
What does the transformations-based focus of the Common Core State
Standards mean?
Nanette Seago WestEd
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Presentation Overview
I. Geometric Transformations and Common Core State Standards
II. Students’ Struggles with Transformations and Similarity
III. Static and Transformations-based approaches
IV. Rectangle Problem & Video Clip Discussion
V. Learning and Teaching Geometry Project’s Research on Teacher and Student Learning
VI. Resources for Resources for PD
Geometric Transformations and the Common Core Standards
Geometric Transformations and the 8th Grade Common Core Standards
Understand congruence and similarity using physical models, transparencies, or geometry software.
1. Verify experimentally the properties of rotations, reflections, and translations
2. Understand that a two-dimensional figure is congruent to another if the second can be obtained from the first by a sequence of rotations, reflections, and translations; given two congruent figures, describe a sequence that exhibits the congruence between them.
3. Describe the effect of dilations, translations, rotations, and reflections on two-dimensional figures using coordinates.
4. Understand that a two-dimensional figure is similar to another if the second can be obtained from the first by a sequence of rotations, reflections, translations, and dilations; given two similar two-dimensional figures, describe a sequence that exhibits the similarity between them.
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ChallengesIn 2011, a national task force of mathematicians, mathematic educators, state leaders, and teacher leaders made recommendations about which CCSS mathematics domains should be targeted as priority areas for professional development and resources in grades K-8.
They targeted Grade 8 geometry as one of the five recommended priority areas, stating:
• Geometry in the Common Core State Standards is based on transformations, an approach that is significantly different from previous state standards. This is a change for students, teachers, and teachers of teachers. Challenges include attention to precision and language about transformations…. The transformational approach to congruence and similarity is likely unfamiliar to many middle grades teachers (McCallum, 2011).
Students’ Struggles with Transformations and Similarity
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Eighth Grade NAEP ItemThis 2007 NAEP item was classified as “Use similarity of right triangles to solve the problem”.
1% of eighth- grade students answered correctly
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Twelfth- Grade NAEP ItemThis 1992 NAEP item was classified as “Find the side length given similar triangle”.
24% of high school seniors answered correctly
Static and Transformations-based Approaches to Similarity
Static Conceptions of Similarity
Focus on comparison of numerical relationships between corresponding parts of similar figures
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3 6
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Focus on setting up and solving proportions that are not connected to geometric meaning
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3 6
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Similarity is conceptualized in discrete terms as a numeric relationship between two figures
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A Transformations-based Conception of Similarity
Similarity is conceptualized as enlarging or reducing figures proportionally to create a class of similar figures.
Focus is on geometric transformations that result in similar figures
Attention is on all possible figures in a similarity class enabled by visual representations of dilating figures
The ratio of lengths of corresponding sides of similar figures is the scale
factor of the dilation
Ratio of lengths within a single figure is invariant across the similarity class
A Geometric Transformations Approach to the 8th Grade NAEP problem
Center of Dilation
A Geometric Transformations Approach to the 12th Grade NAEP problem
Center of Rotation
A Geometric Transformations Approach to the 12th Grade NAEP problem
Center of Dilation
A two-dimensional figure is similar to another if the second can be obtained from the first by a sequence of rotations, reflections, translations and dilations
Transformations-Based Definitions of Congruence & Similarity
A two dimensional figure is congruent to another if the second can be obtained from the first by a sequence of rotations, reflections, and translations.
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Rectangle Problem & Randy
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Rectangle Problem
Which rectangles are similar to rectangle a?
How is Randy solving the problem? What relationships is
he attending to?
Unpacking Randy’s Method
• What did Randy do? (What was his method?)
• Why might we argue that Randy’s conception of similarity is more transformations-based than static-based?
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Representing Similar Rectangles as Dilation Images
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Learning and Teaching Geometry Project’s Research on Teacher
and Student Learning
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Learning and Teaching Geometry Project Overview
• Funded by the U.S. National Science Foundation • Developing video case-based professional
development materials
• Targeted for mathematics teachers of grades 5-10
• The materials include:– 1 Foundation Module (10, 3-hour sessions)– 4 Extension Modules (2, 3-hour sessions)
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Learning and Teaching Geometry Project Staff
• Staff: Nanette Seago (PI), Mark Driscoll (Co-PI), Jennifer Jacobs, Michael Matassa, Johannah Nikula, Patrick Callahan, Hilda Borko
• Advisory Board: Harold Asturias, Tom Banchoff, Phil Daro, Megan Franke, Karen Koellner, Glenda Lappan, Hung-Hsi Wu
• Evaluation Team: [Horizon Research, Inc.] Dan Heck, Kristen Malzahn, Courtney Nelson
Design• Built around authentic video clips
– 3-6 minutes in length – Grades 5-9 classrooms
• Video clips intended as objects of inquiry, not exemplars
• Well-specified facilitator support materials:– Detailed agendas and resources – Make explicit the goals and underlying core principles
• Focus on geometric similarity
LTG Foundation Module
Ten 3-hr SessionsSession 1
A dynamic, transformatio
nal view of congruence
Session 2A dynamic,
transformational view of Similarity
Session 3Relationship
Between Dilation and
Similarity
Session 4Properties of
Dilation
Session 5Preservation of Angles & Proportional
Lengths through Dilation
Session 6Ratios
Within and Between Similar Figures
Session 7Ratios
Within and Between Similar Figures. Part 2
Session 8Connections
between Similarity, Slope &
Graphs of Linear
Functions
Session 9Area of Similar Figures
Session 10Closure and Re-capping of Big Ideas
DefiningCongruence and Similarity
Relationships and Attributesof Similar Figures
Connections Closure
Teacher Learning Goals:
• To examine a transformations-based view of similarity, and geometry in general
• To enhance teachers’ mathematical knowledge for teaching similarity
• To gain insight into students’ developing conceptions of similarity
In each 3-hour PD session, teachers:
• Grapple with the same mathematical task(s) the videotaped students tackled
• View, analyze & discuss the video clip(s)
• Consider issues around content, student thinking, and pedagogy
Research Questions(Horizon Research, Inc.)
• What is the impact of participation in the LTG professional development program on teachers’ mathematical knowledge for teaching?
• What is the impact of teachers’ participation in the LTG program on their students’ performance in geometry?
Field Test Sites
Field Test Participants
• 126 Participants o 87 treatmento 39 comparisono Mix of K-12 in-service teachers, teacher
leaders/coaches and pre-service teachers
Field Test Data Collection Activities
• Facilitator & Teacher Questionnaire• Teacher Content and Embedded Assessments• Facilitator Session Logs• Professional Development Observation• Facilitator Interview• Student Content Assessment (2010-11 only)
Teacher Content and Embedded Assessments
Teacher Content Assessment– Geometry Assessment– 25 multiple-choice items (pre/post)
• Congruence Transformations• Dilation• Properties of Similarity• Ratios and Proportions• Scaling
Embedded Assessments– Video Analysis [Randy] (pre/post)– Sorting Rectangles Math Task (pre/post)
LTG Teacher Content Assessment Field TestPercent Correct Scores
Pre Post Gain Scores
Effect SizeMean Mean
Treatment(N=83) 63.66 72.39†
+8.730.39
Comparison(N=38) 65.79 67.47 +1.68
†On average, teachers in the treatment condition demonstrated significant improvements in percent correct scores while comparison teachers did not (repeated-measures ANOVA; p < 0.05).
Embedded Teacher Assessments: Video Analysis & Sorting Rectangles Task
Treatment teachers significantly improved on 2 of the 3 math task questions, and on 3 of 3 video analysis questions.
Comparison teachers didn’t demonstrate significant improvement on any of the 6 questions.
Session 1A dynamic,
transformational view of congruence
Session 2A dynamic, transformational view
of Similarity
Session 3Relationship
Between Dilation and
Similarity
Session 4Properties of
Dilation
Session 5Preservation of Angles & Proportional
Lengths through Dilation
Session 6Ratios
Within and Between Similar Figures
Session 7Ratios
Within and Between Similar Figures, Part 2
Session 8Connections
between Similarity, Slope &
Graphs of Linear
Functions
Session 9Area of Similar Figures
Session 10Closure and Re-capping of Big Ideas
DefiningCongruence and Similarity
Relationships and Attributesof Similar Figures
Connections Closure
RandyRandy
Math task
Math task
SORTING RECTANGLES TASK
LTG Student Geometry Assessment Field TestPercent Correct Scores
Pre Post Gain Scores
Effect SizeMean Mean
Treatment(N=162) 36.42 45.28† +8.86
0.49 Comparison
(N=104) 42.69 45.00 +2.31
† On average, students of teachers in the treatment condition demonstrated significantly larger gains in percent correct scores than students of comparison teachers (repeated-measures ANOVA; p < 0.05).
Tentative Conclusions
• The LTG PD program appears to improve teachers’ mathematical knowledge for teaching in the area of transformations-based geometry.
• Students of the participating teachers appear to show improved knowledge of transformations-based geometry.
Resources for PD
Some Potential Resources for Leaders
LTG Resources: Learning and Teaching Geometry Video Case Materials, WestEd. Expected
publication date: Spring 2014
Field Guide to Geometric Transformations, Congruence & Similarity available at http://www.wested.org/cs/we/view/rs/1246
NCSM: Illustrating the Standards for Mathematical Practicehttp://www.mathedleadership.org/ccss/itp/index.html
Other Resources:
Illustrative Mathematics Project: Tools for the Common Core http://commoncoretools.me/2011/01/16/the-illustrative-mathematics-project/
Transformational Geometry, Richard Brown (1989)
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Transformations-based Definitions
NCSM Modules
Congruence & Similarity Module
• Participants examine the meaning of defining congruence and similarity through transformations as articulated in the Common Core State Standards.
• Participants are asked to compare and contrast static definitions of congruence and similarity with dynamic definitions of congruence and similarity.
• Participants consider implications for instruction that the dynamic definitions have on teaching and learning mathematics.
Similarity, Slope, Lines Module
• Participants unpack the connection between similarity, slope, and the graphs of linear functions by doing mathematical tasks, analyzing student thinking, and exploring a computer-based applet.
• Participants consider strategies to support students' to reason mathematically and learn to use precise language in their explanations.
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