The Common Core standard includes the phrase “a hierarchy based on properties” regarding classification of polygons. Students need to understand that some classifications or groups are inclusive of all examples of other groups, and some classifications are inclusive of some other examples.
These activities use observation and recording of the key properties of quadrilaterals, questioning designed to clarify definitions, and Venn diagrams to help students classify quadrilaterals logically and precisely. This is best but not necessarily done with physical quadrilaterals.
There are several properties essential to classifying quadrilaterals; students list all those for each quadrilateral, and then discuss the implications. Students are helped to deduce the resolution to these questions like, “Is a square a rectangle?”, or “Is a rectangle a parallelogram?” We clarify the meaning and importance of parallel sides, and what parallelograms, rhombi, and trapezoids are. Students encounter more accurate ways of naming and describing these shapes than they knew before.
The inclusion of rectangles, squares, and rhombi in the set of parallelograms is modeled clearly and experientially with The Parallelogram Machine and The Rhombus Machine. The file includes templates with which you can make several different sizes of rectangles and squares that morph into parallelograms and rhombi in students’ hands.
A Smart Notebook 14 file is included.
Common Core Standards:
4.G.2: “Classify two-dimensional figures based on the presence or absence of parallel or perpendicular lines...”
5.G.4: “Classify two-dimensional figures in a hierarchy based on properties...”
Subject: Math, Geometry, Logic
Level: Grades 4 – 6
Length/Duration: 9 pages of student work, 2-3 days