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Building Geometric Thinking with Hands- On Tasks & in Virtual Environments Jean J. McGehee University of Central Arkansas.

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Presentation on theme: "Building Geometric Thinking with Hands- On Tasks & in Virtual Environments Jean J. McGehee University of Central Arkansas."— Presentation transcript:

1 Building Geometric Thinking with Hands- On Tasks & in Virtual Environments Jean J. McGehee University of Central Arkansas

2 Today Geometric Habits of Mind—from Paper Folding to Using Sketchpad—in the context of rich problems Transformations: a Connecting big idea The role of good definitions: Quadrilaterals Connecting Sketchpad to the Number and Algebra strands


4 Goals of FGT Strengthen understanding of geometry Enhance capacity to recognize and describe geometric thinking Increase attention to students’ thinking Enhance understanding of students’ geometric thinking Prepare to advance students’ geometric thinking

5 The Geometry Curriculum in Arkansas Let’s take a quick look at the frameworks..\..\..\Desktop\frameworks\geo metry_06.doc..\..\..\Desktop\frameworks\geo metry_06.doc Even my student interns at UCA notice how much repetition there is in the curriculum—e.g. The Triangle Sum We do need to revisit ideas—but we need to do it with value added.

6 The FGT Project in NE Arkansas Two school districts in grades 5-11 I wanted the teachers at all grade levels to share their strengths and understand the curriculum vertically. I wanted them to share their students work and their ideas so that they gained an appreciation for each other.

7 All levels benefited. The 5 th and 6 th grade teachers enjoyed the hands on activities, and these very same activities are useful even after the high school geometry course. With Algebra II and beyond we really downplay geometry—yet these kids have to take the ACT or SAT. With these problems they will also have to explain their thinking.

8 It’s hard to get teachers to focus on content for fun when they deal with state tests. Cathy (6 th grade) and Cindy (Geometry) are teachers who trust rich problems, inquiry investigations, and projects BEFORE the State Tests as a means to prepare for criteria tests---Their scores show it!!

9 Another teacher from Arkansas reported: One of my 6th grade FGT participants told me that her students' scores on the Arkansas assessment increased from 46% proficient and advanced in 2005 to 68% in 2006. That was great news, but it gets better. She credits the increase to their better understanding of geometry and measurement than in years past. She says that is a direct result of the problems we did (and she did with her students) in FGT. In fact, after the testing her students told her that the problems on the test were like what they had done in class "except they didn't give us any paper to fold".

10 Structure of FGT The Structured Exploration Process guides the activities in each part of FGT sessions. There is a cycle of doing math and exploring student thinking. The Geometry Habits of Mind framework provides a lens to analyze geometric thinking.

11 Three content strands Focus the work on different important areas of geometry & measurement. They are:  Properties  Transformations  Measurement

12 The Structured Exploration Process Stage 1: Doing mathematics Stage 2: Reflecting on the mathematics Stage 3: Collecting student work Stage 4: Analyzing student work Stage 5: Reflecting on students’ thinking

13 FGT G-HOMs Reasoning with Relationships Generalizing Geometric Ideas Looking for Invariants Balancing Exploration & Reflection

14 More about FGT and G-HOMs later First, let’s do exercise our own geometric thinking  Folding, Making Squares, Congruent Halves  Paper-Folding & Constructions  Tangrams  Dissecting Shapes  Comparing Triangles We will start in detail—but I may have to summarize the latter problems.

15 Do Math--Ideally Work problem individually 5-10 minutes Work problem in groups 25 minutes  Last 10 minutes groups prepare report either on transparency or chart paper Reflect on the problem & Identify G-HOMs 25-30 minutes

16 Let’s do more with paper folding-Start at b b. Construct a triangle with exactly ¼ the area of the original square. Explain how you know it has ¼ the area: c. Construct another triangle that also has ¼ the area, which is not congruent to the first one you constructed. Explain how you know is has ¼ the area: d. Construct a square with exactly /12 the area of the original square. Explain how you know it has ½ the area: e. Construct another square, also with ½ the area which is oriented differently than the one you constructed in (d). Explain how you know it has ½ the area

17 Review: Investigating Area by Folding Some comments on the challenge problem. Recall that it was relatively easy to find a square that is ¼ of the original. We all found one square that is ½ of the original. I want to show you a quilter’s approach Also I want to show you this problem in a fun book.

18 A Quilter’s Solution—does it work?

19 The Number Devil This little devil beguiles Robert into dreams to give him a glimpse of the beauty & power numbers. In this case, the square root of 2.

20 Student intern gave students two squares and asked How many black squares fit into the red square? Show how you knew this.

21 Hands-On & Sketchpad I have learned both in PD and classes to start with Hands-On Making a gallery of chart paper reports and walking through the gallery is a wonderful way to summarize the problem. Sketchpad provides a way to solidify conjectures and make a bridge to proof.

22 Basic Paper Folding The perpendicular bisector is the most basic fold. Who can describe this for me? How do you know? Construct a line that is parallel to your original segment. Describe your method. How do you know your new line is a parallel line to the original segment? Now start with a fresh segment each time and construct: an isosceles triangle an equilateral triangle a square

23 Analyzing Student Work What are the important mathematical ideas in the problem? What strategies do you want to foster and why? What is the evidence that a student used a strategy? Is it related to a G-HOM?

24 Student work on Paper Folding What do you think students typically do? How do you think students use geometric language?  Go Back to the Demand of the Task.  Are we actually requiring students to write and speak the language of geometry?  Or do we practice Multiple Choice items and work problems in which the language task is low?

25 Paper Folding related toTangrams You are familiar with the square, but can you make a rectangle that are not squares—2 ways?

26 Let’s explore the area problems Tangrams on Sketchpad More shapes with the same area—an understanding based on properties rather than memorized formulas.

27 Dissecting Shapes The ability to dissect and transform shapes is important. Students are also exploring invariance and properties.

28 Dissecting Shapes--Conclusions

29 Comparing Triangles Start with a piece of paper (you can also use different size rectangular paper). Fold your paper so that point A is directly on top of point C. Some triangles appear. In the picture below—you should see 3 triangles.

30 Comparing Triangles Start with another piece of paper. This time fold A onto any point between D and C. Again there are 3 triangles which are all right triangles. What else do you notice about the triangles?

31 In your report, consider 1. Describe your construction method in pictures and words. 2. Before you tried your method, why did you think it would work? 3. Were there methods you tried that didn’t work? What were they? 4. What are the properties of the constructed shapes? How do you know your shape has these properties.

32 Sorting by Symmetry & more Advanced Properties

33 Transformations

34 Mira—a transition to the Computer Rotation Translation Finding Centers of Rotation

35 Coordinate work Wumps

36 Dilations

37 The Role of Definitions To me it appears a radically vicious method, certainly in geometry, supply a child with ready made definitions, to be memorized after being more or less carefully explained....The evolving of a workable definition by the child’s own activity stimulated by appropriate questions, is both interesting and highly educational. Bechara, Blandford, 1908

38 Development of Definitions Descriptive Defining Constructive Defining Hierarchical vs. Partition Defining The Role of Construction & Measurement

39 Quadrilateral Activities Geometric Structures: If we had time, we would go through these activities—you may think they are repetitive, but students need all of these experiences to deal more flexibly with properties and definitions. Let’s do Sketchpad activity from Restructuring Proof –think about this activity from High and Low levels.

40 Geometric Thinking Task Demand Categories Memorization: What is the formula for the area of a triangle? State the SAS congruence postulate Procedures without Connections: Given this drawing, find the area of the triangle? Given these marked triangles, are they congruent? Procedures with Connections: Draw a rectangle around the triangle and find the area. Fold the paper and identify the relationship between the triangles. Doing mathematics: If we don’t want to count the squares that cover the triangle, how can we find the area? Verify by measurement; Reason through your conjecture about the triangles.

41 Reasoning with relationships Actively looking for and applying geometric relationships, within and between geometric figures. Internal questions include: “How are these figures alike?” “In How many ways are they alike?” “How are these figures different?” “What would I have to do to this object to make it like that object?”

42 Generalizing geometric ideas Wanting to understand and describe the "always" and the "every" related to geometric phenomena. Internal questions include: “Does this happen in every case?” “Why would this happen in every case?” “Can I think of examples when this is not true?” “Would this apply in other dimensions?”

43 Investigating invariants An invariant is something about a situation that stays the same, even as parts of the situation vary. This habit shows up, e.g., in analyzing which attributes of a figure remain the same when the figure is transformed in some way. Internal questions include: “How did that get from here to there?” “What changes? Why?” “What stays the same? Why?”

44 Sustaining reasoned exploration Trying various ways to approach a problem and regularly stepping back to take stock. Internal questions include: "What happens if I (draw a picture, add to/take apart this figure, work backwards from the ending place, etc.….)?" "What did that action tell me?"

45 Sketchpad is not limited to Geometry Making figures for any handout-the Pentagon The capabilities of the hide/show buttons and easy text abilities make it ideal for puzzles It gives a visual representation of algebra- graphs and algebra tiles.




49 Liz’s Pattern

50 Factoring I have a PowerPoint for you and Sketches that are interactive with the tiles.

51 Formulas & Graphing Making sense of geometric formulas A sketch that could be done on NSpire— but it works on the computer, too

52 The Possibilities are Endless! I have a CD for you with many sketches— start playing with them—imagine how you can use them—even change them. When you think of a concept for a lesson—visualize the geometric representation of it, then either play with GSP or e-mail me. Any questions? Comments?

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