Khan Academy on a Stick
Points, lines, and planes
This topic introduces the basic conceptual tools that underpin our journey through Euclidean geometry. These include the ideas of points, lines, line segments, rays, and planes.

Euclid as the Father of Geometry
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Euclid and his Elements (and how much Abraham Lincoln liked them)

Language and Notation of Basic Geometry
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Understanding basic ideas in geometry and how we represent them with symbols

Lines, Line Segments, and Rays
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Difference between lines, line segments, and rays
 Specifying planes in three dimensions

Language and Notation of the Circle
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Formal definition of a circle. Tangent and secant lines. Diameters and radii. major and minor arcs

The Golden Ratio
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An introduction to one of the most amazing ideas/numbers in mathematics

Identifying Rays
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Identifying Rays
Introduction to Euclidean geometry
Roughly 2400 years ago, Euclid of Alexandria wrote Elements which served as the world's geometry textbook until recently. Studied by Abraham Lincoln in order to sharpen his mind and truly appreciate mathematical deduction, it is still the basis of what we consider a first year course in geometry. This tutorial gives a bit of this background and then lays the conceptual foundation of points, lines, circles and planes that we will use as we journey through the world of Euclid.