# Geometry

Geometry (X)

## Coordinate Plane: Reflecting Points

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This tutorial explains that a reflection point is the mirror point on the opposite axis--like looking at a mirror image of yourself, but flipped.

## Surface Area: Nets of Polyhedra - Introduction

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A polyhedron ("polyhedra" is plural) is nothing more than a 3 dimensional shape with flat surfaces and straight edges. (Think: cube.)

## Area and Perimeter of Polygons: Finding Area by Breaking up the Shape

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Find the area of odd-looking geometric figures by breaking the figure up into smaller, simple geometric shapes, then calculate and total their areas.

## Surface Area: Using Nets of Polyhedra

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Surface area is the sum of all the areas of all the shapes that cover the object's surface. Let's use the net of polyhedra as an example.

## Perimeter and Area of Non-Standard Shapes: Area of a Parallelogram

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What's interesting about the opposite sides of a parallelogram? That's right....they are parallel! Let's find the area--base x height.

## Machinist | Great Job!

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Machinist John Morris uses a computerized machining center to produce complicated parts out of metal & plastic that are accurate to fractions of an inch.

## Real-World Expressions and Equations: Tip Jar

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Examine whether the common practice of tipping 20% of a restaurant bill for great service is fair. This video focused on different ways to visualize the current method of tipping and proposed potential changes to the standard practice. This video was submitted through the Innovation Math Challenge, a contest open to professional and nonprofessional producers.

## Real-Life Math | Woodworker

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Listen to a master craftsman explain many of the ways that mathematics is used in woodworking, including number operations; geometry; ratios and proportions; and measurement, in this video from KAET. In the accompanying activity, students will draw a scale drawing of an object in their classroom.

## Volume of a Cone

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Watch an animated demonstration of finding the volume of a cone and cylinder with the same base and height in this video from KCPT. In the accompanying classroom activity, students estimate the relative volume of a cone and cylinder with the same base and height. They test their estimates by filling the cone and pouring the contents into the cylinder and then use the cylinder volume formula as a basis for predicting the cone volume formula. To get the most from the lesson, students should know the formulas for the area of a circle and volume of a cylinder.

## Pythagorean Theorem in Kapa Design

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Listen to a master quilt maker discuss the relationship between art and mathematics as she demonstrates how the Pythagorean theorem is an important part of the pattern design process in this video from the Center for Asian American Media. This resource is part of the Math at the Core: Middle School Collection.

## Negative Exponents as Fractals

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Determine the relationship between graphic patterns and what they represent mathematically. This video focuses on how fractals can be a visual representation of negative exponents, which are a way to express repeated division. This video was submitted through the Innovation Math Challenge, a contest open to professional and nonprofessional producers.

## Positive Exponents as Fractals

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Explore the relationship between graphic patterns and their mathematical representation. This video focuses on how fractals can be a visual representation of positive exponents. This video was submitted through the Innovation Math Challenge, a contest open to professional and nonprofessional producers.

## Skateboarding

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In this video segment from Cyberchase, Bianca injures her ankle while skateboarding and is confined to her bed. She has trouble reaching a few objects from her bed until her friend gives her a device made up of collapsible parallelograms. Bianca finds that by adjusting the parallelograms, she can now extend her reach.

## Points of Origin

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This animation from KET illustrates how an origin is used for positive and negative measurement along a straight line and on a flat plane. It also shows how an origin, latitude, and longitude identify locations on Earth and explores how measuring temperature differs from measuring height or weight.

## Finding the Circle's Center | Cyberchase

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In this video segment from Cyberchase, the CyberSquad must reclaim the Totally Rad Ring by making an exact duplicate. To do that, they must determine the radius of the ring and the exact center. The ring then must be placed in the exact center of a circle.