Pattern Blocks The Forgotten Tool in Middle School Jennifer Hagman
[email protected] Jennifer Moffett
[email protected] In This Session You will 2 Learn… How our understanding of definitions of shapes may have shifted The geometric progression with respect to angle relationships and dilations How pattern blocks can be used as a tool to investigate angle relationships and dilations Which Standards of Mathematical Practices are supported through these types of investigations 3 Defining Shapes Shapes 4 What do you notice? What are the names for each shape? Why do some shapes have more than one name? Defining Shapes Always, Sometimes, Never A triangle is a parallelogram. A square is a parallelogram. A square is a rectangle. A rectangle is a square. A trapezoid is a parallelogram. A parallelogram is a trapezoid. Adapted from Illustrative Mathematics What is a trapezoid? Moffett and Hagman are studying parallelograms and trapezoids. They agree that a parallelogram is a quadrilateral with two pairs of parallel sides. What is a trapezoid? Hagman says, A trapezoid has one pair of parallel sides and a parallelogram has two pairs of parallel sides. So a parallelogram is also a trapezoid. Moffett says, No- a trapezoid can have only one pair of parallel sides. Hagman says, That’s not true. A trapezoid has at least one pair of parallel sides, but it can also have another. What is the difference between their definitions for a trapezoid? Which picture represents the relationship between trapezoids and parallelograms for each definition? a. b. c. So Who is Correct? Hagman Moffett Inclusivity The inclusive definition sets up a relationship between parallelograms and trapezoids that is exactly analogous to the relationship between squares and rectangles; the definition for rectangles includes squares in the same way that the inclusive definition of trapezoids includes parallelograms.