At this level it is not expected that students can create a complete Venn diagram of all the classes of quadrilateral. Provoke students to think about relationships between classes of quadrilaterals.Group the shapes by the properties listed in 6 as much as possible and create labels for the class of shapes and criteria for inclusion on the back of each card. They might look for similar side lengths. For example, they might notice symmetry or attend to the size of one angle. Students may notice common properties shared between shapes that are not listed above. Adjacent means “next to” so the equal sides meet at a corner.Ī four-sided polygon that meets this criterion is called a kite.Ī four-sided polygon that has all sides equal is called a rhombus.Ī four-sided polygon that has unequal sides and angles is sometimes called a scalene quadrilateral. Two pairs of equal sides that are adjacent. They might attend to:Ī four-sided polygon with two pairs of parallel sides is called a parallelogram.Ī four-sided polygon with only one pair of parallel sides is called a trapezium. Look for students to find similar shapes. All the shapes have four sides so look for a different similarity. I want you to find someone who has a shape that is the same as your shape. For example, a rhombus has four equal sides but does not need to have right-angles (actually, a square is a type of rhombus).Īsk the students who placed rectangles and squares in the diagram to choose another shape card from the copymaster. Challenge them to explain why by referring to the definitions. Some students may believe their shape belongs in the ellipses. Ask them to justify where they locate their shapes by referring to the definitions on the back of the cards. Who is certain they know where to put their shape?Ĭhoose the students with squares and rectangles. Give students time to think about where they will place their shape. Put the other quadrilateral cards from the copymaster on the floor or tabletop.Ĭhoose a shape from the set and decide where in the diagram it should go. The important point is that the criteria for rectangles apply to squares with one extra requirement all four sides are equal (in length).
What shall we write on the back of the “squares” card? On the back of each card write the defining properties. Use cards to name the rings in the Venn Diagram as “rectangles” and “squares”.Tell students that a polygon is a flat (2-D) shape that is enclosed by sides.ĭoes a square have four sides and four right-angles? “A four-sided polygon that has four right angles.” Look up the definition of a rectangle using an online mathematics dictionary. The rectangle has two long sides and two short sides. Examples might be:īoth shapes have L shaped (right-angled) corners.
Look for students to make statements about the properties of the two shapes. How can a square also be a rectangle?Īfter a suitable time gather the group to discuss their ideas. Place one square and one rectangle in the Venn diagram as shown below: I made these spaces to show that whatever shapes are in here (trace around small ellipse) also belong in here (trace around large ellipse).
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