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Classify Shapes in a Hierarchy (Quadrilaterals & Triangles)

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- How to classify quadrilaterals in a hierarchy based on their attributes.
- We’ll also learn how to classify triangles in a hierarchy.
- And we will see that this knowledge can help us pack for summer camp and even plan a party!
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Discussion Questions
- Before VideoWhat does the measurement of an angle tell you?ANSWER
It tells you the size of the turn, or amount or rotation between the two adjacent lines, rays, or line segments.
It means that one side of the shape is a mirror image of the other.
The tracks are parallel because they continue on without ever getting closer to one another, or farther apart.
The railway ties are perpendicular to the tracks because they cross at a 90° angle.
A closed shape has all of the edges connecting at endpoints, so there are no gaps in the perimeter (distance around the outside of a shape). A closed shape has area.
- After VideoWhat does it mean for parallelogram to be a subgroup of quadrilateral?ANSWER
It means that a parallelogram has all the properties of a quadrilateral, plus the properties specific to parallelograms.
The square inherits the properties of the kite (two sets of adjacent sides with equal length) through the rhombus (four equal sides), and the properties of the parallelogram (two sets of parallel sides) through the rectangle (all right angles). Because the square keeps the properties that define its supergroups, a square is also a parallelogram and a kite.
No. A triangle and a quadrilateral are both classified on the property of “number of sides.” A triangle is a shape with exactly three sides, and a quadrilateral is a shape with exactly four sides. This means that a shape cannot be both a triangle and a quadrilateral.
(Exclusive definition) No. A trapezoid is a shape with exactly one set of parallel sides, so a parallelogram cannot be a trapezoid. (Inclusive definition) Yes. A trapezoid is a shape with at least one set of parallel sides, so parallelogram is a subgroup of trapezoid.
A hierarchy is a system of classification based on sets of properties that become more and more specific as you move down the hierarchy. All subgroups retain all the properties of their supergroups, so in geometry, shapes inherit the properties of the categories above them in the hierarchy.
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Vocabulary
- Property DEFINE
A characteristic that is true of a geometric shape in a given category.
- Category DEFINE
A classification of shapes with a defined set of properties.
- Polygon DEFINE
A closed shape with all straight sides.
- Angle DEFINE
A measurement of the rotation between two lines with a common endpoint.
- Right Angle DEFINE
An angle that measures 90°.
- Acute Angle DEFINE
An angle that measures between 0° and 90°.
- Obtuse Angle DEFINE
An angle that measures between 90° and 180°.
- Triangle DEFINE
A three-sided polygon.
- Equilateral Triangle DEFINE
A triangle where all sides have an equal length.
- Isosceles Triangle DEFINE
A triangle with two equal sides.
- Scalene Triangle DEFINE
A triangle with no sides the same length.
- Quadrilateral DEFINE
A four-sided polygon.
- Parallelogram DEFINE
A quadrilateral with two sets of parallel sides.
- Hierarchy DEFINE
A categorization method where things are sorted into more and more specific groups, and the subgroups retain all the properties of the supergroup.
- Supergroup DEFINE
A group that can be divided into smaller subgroups based on a property of the items you are sorting.
- Subgroup DEFINE
A group with a more specific property than the supergroup. For example, of the supergroup “all US states,” there is a subgroup “states on the West coast.”
- Rectangle DEFINE
A parallelogram with all right angles.
- Rhombus DEFINE
A quadrilateral with 4 equal sides and two pairs of parallel sides.
- Trapezoid (inclusive) DEFINE
A quadrilateral with at least one set of parallel sides.
- Trapezoid (exclusive) DEFINE
A quadrilateral with exactly one pair of parallel sides.
- Pentagon DEFINE
A five-sided polygon.
- Hexagon DEFINE
A six-sided polygon.
- Heptagon DEFINE
A seven-sided polygon.
- Octagon DEFINE
An eight-sided polygon.
- Nonagon DEFINE
A nine-sided polygon.
- Property DEFINE
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Reading Material
Download as PDF Download PDF View as Seperate PageWHAT IS CLASSIFYING SHAPES IN A HIERARCHY (QUADRILATERALS & TRIANGLES)What are the properties of shapes? 2D shapes are flat and can hold area. When all the sides are straight, the shape is a polygon. These shapes have properties like side lengths and angles.
To better understand classifying shapes in a hierarchy (quadrilaterals & triangles)…
WHAT IS CLASSIFYING SHAPES IN A HIERARCHY (QUADRILATERALS & TRIANGLES). What are the properties of shapes? 2D shapes are flat and can hold area. When all the sides are straight, the shape is a polygon. These shapes have properties like side lengths and angles. To better understand classifying shapes in a hierarchy (quadrilaterals & triangles)…LET’S BREAK IT DOWN!
Triangle Party
We are having a Triangle Party! We have many familiar objects, all with three straight sides. One is a chip with all equal length sides. Another is a sail for our model sailboat. It has three different side lengths and one 90° angle. We know that triangles can have acute angles, meaning angles smaller than 90°, obtuse angles that are bigger than 90°, or right angles that are equal to 90°. When the sides of a triangle are all the same length, it is equilateral. If only two are the same length, it is isosceles, and if all the lengths are different, it’s scalene. What kind of triangles are our objects? The chip is an equilateral triangle because of its three equal sides. The sail is a right scalene triangle because all the lengths are different, and it has a 90° angle. Try this yourself: What kind of triangle is a coat hanger if it has two equal-length sides and one angle larger than 90°?
Triangle Party We are having a Triangle Party! We have many familiar objects, all with three straight sides. One is a chip with all equal length sides. Another is a sail for our model sailboat. It has three different side lengths and one 90° angle. We know that triangles can have acute angles, meaning angles smaller than 90°, obtuse angles that are bigger than 90°, or right angles that are equal to 90°. When the sides of a triangle are all the same length, it is equilateral. If only two are the same length, it is isosceles, and if all the lengths are different, it’s scalene. What kind of triangles are our objects? The chip is an equilateral triangle because of its three equal sides. The sail is a right scalene triangle because all the lengths are different, and it has a 90° angle. Try this yourself: What kind of triangle is a coat hanger if it has two equal-length sides and one angle larger than 90°?Hanging Pictures
We are in art class and need to hang pictures in their matching frames with the same shape. All the frames are sorted into their most specific category of 2D shape, but we still need to sort the pictures. All the frames have four straight sides, so we know they are all quadrilaterals. Some frames have one set of parallel sides; these are trapezoids. Others have two sets of parallel sides; these are parallelograms. Some of the parallelograms have right angles, which means they are rectangles. Your friend points to a pile of frames that are parallelograms that have four equal sides but no right angles. Those are rhombi, or a rhombus if we only have one. The last pile is even more specific, with 4 right angles and 4 equal sides. Those are squares! Your first picture has four straight sides, two pairs of parallel sides with different lengths. That means the most specific category we can choose is a parallelogram. That is where we will find the matching frame! Try this yourself: There is a picture with four equal side