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Developing Spatial Mathematics. Richard Lehrer Vanderbilt University. Thanks to Nina Knapp for collaborative study of evolution of volume concepts. Why a Spatial Mathematics?. HABITS OF MIND. Generalization (This Square --> All Squares). Definition. Making Mathematical Objects.
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Developing Spatial Mathematics Richard Lehrer Vanderbilt University Thanks to Nina Knapp for collaborative study of evolution of volume concepts.
Why a Spatial Mathematics? HABITS OF MIND • Generalization (This Square --> All Squares) • Definition. Making Mathematical Objects • System. Relating Mathematical Objects • Relation Between Particular and General (Proof) • Writing Mathematics. Representation.
Capitalizing on the Everyday • Building & Designing---> Structuring Space • Drawing ---> Representing Space (Diagram, Net) • Counting ---> Measuring & Structuring Space • Walking ---> Position and Direction in Space
Pathways to Shape and Form • Design: Quilting, City Planning (Whoville) • Modeling: The Shape of Fairness • Build: 3-D Forms from 2-D Nets • Classify: What’s a triangle? A perfect solid? • Magnify: What’s the same?
The Shape of Fairness Game of Tag-- What’s fair? (Gr 1/2:Liz Penner)
The Fairest Form of All? Investigate Properties of Circle, Finding Center Develop Units of Length Measure Shape as Generalization
What’s a Triangle? What’s “straight?” What’s “corner?” What’s “tip?” 3 Sides, 3 Corners
Building and Defining in K Kindergarten: “Closed”
Modeling 3-D Structure • Physical Unfolding--> Mathematical Representation
Shifting to Representing World “How can we be sure?”
Student Investigations Good Forum for Density
Measuring Space • Structuring Space • Practical Activity
Children’s Theory of Measure • Build Understanding of Measure as a Web of Components
Constructing Arrays Grade 2: 5 x 8 Rectangle as 5 rows of 8 or as 8 columns of 5 (given a ruler) L x W = W x L, rotational invariance of area
Structuring Space: Volume Appearance - Reality Conflict
Making Counts More Efficient • Introducing Hidden Cubes Via Rectangular Prisms (Shoeboxes) • Column or row structure as a way of accounting for hidden cubes • Layers as a way of summing row or column structures • Partial units (e.g., 4 x 3 x 3 1/2) to promote view of layers as slices
Extensions to Modeling Nature Cylinder as Model Given “Width,” What is the Circumference? Why aren’t the volumes (ordered in time) similar?
Yes, But Did They Learn Anything? • Brief Problems (A Test) - Survey of Learning • Clinical Interview - Strategies and Patterns of Reasoning
Comparative Performance Grade 2 Hidden Cube 23% ---> 64% Larger Lattice 27% ---> 68% Grade 3 (Comparison Group, Target Classroom) Hidden Cube 44% vs. 86% Larger Lattice 48% vs. 82% Cylinder 16% vs. 91% Multiple Hidden Units: 68%
Interviews • Wooden Cube Tower, no hidden units (2 x 2 x 9) • - Strategies: Layers, Dimensions, Count-all • Wooden Cube Tower, hidden units (3 x 3 x 4) • - Strategies: Dimensions, Layers, Count-all • Rectangular Prism, integer dimensions, ruler, some cubes, grid paper • -Strategies: Dimension (including A x H), Layer, Count-All • NO CHILD ATTEMPTS TO ONLY COUNT FACES AND ONLY A FEW (2-3/22) Count-all.
Interviews • Rectangular Prism, non-integer dimensions • -Strategies: Dimension (more A x H), Layer, Only 1 Counts but “not enough cubes.” • Hexagonal Prism • - Strategy A x H (68%) [including some who switched from layers to A x H]