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Explore Geometry Bisected Chord A chord is a line segment where the endpoints of the segment are on a circle. When one bisects the chord of a circle, some interesting properties emerge.
Explore Geometry How Eratosthenes Calculated the Circumference of the Earth While Eratosthenes was not the first to estimate the circumference of the earth, his was the most accurate of the ancient estimates. Here is how he did it. PDF Version
Geometric Proofs Proof: The summit angles of a Saccheri Quadralateral are Congruent A Saccheri Quadralateral is an important construction in Hyperbolic Geometry. It can be used to show many useful properties of Hyperbolic Geometry.
Geometric Proofs Proof: The segment connecting the midpoints of the summit and base line segments of a Saccheri Quadralateral is perpendicular to both. A Saccheri Quadralateral shows what parallel means in Hyperbolic Geometry.
E-Books Chinese Education From a Western Viewpoint by Yen Sun Ho I find this to be an interesting book. Through Yen Sun Ho's comparison of Chinese education to European and U.S. education, he provides a snapshot of education in 1912. Of particular interest to me was the comparison of the cultures and philosophies that surrounded these educational systems.
Worksheet Chinese Proof of the Pythagorean Theorem The Chinese proof of the Pythagorean Theorem is easier to teach and understand than the Euclid's proof from his book Elements. This worksheet includes a cutout to reproduce the proof with paper shapes.
Worksheet Cramer's Rule Worksheet This worksheet is a learning aid for teaching Cramer's rule.
Worksheet How Eratosthenes Calculated the Circumference of the Earth. This one page worksheet briefly reviews the history about and methods used by Eratosthenes when he calculated the circumference of the earth.
Lesson Plan Finding the Circumference of the Earth This lesson focuses on using the estimation of the circumference of the earth to reinforce basic geometric properties of circles and parallel lines. The lesson continues with using Eratosthenes method to estimate the circumference of the earth.
Worksheet Circumference of the Earth Worksheet This worksheet provides a framework for using Eratosthenes method for measuring the circumference of the earth.
Lesson Plan Introduction to Negative Numbers This lesson introduces the student to negative numbers using the concepts of magnitude and direction in both visual and kinesthetic frameworks.
Rubric Rubric for negative numbers creative activity. This rubric accompanies the lesson Introduction to Negative Numbers.
Rubric Rubric for student's descriptions of negative numbers. This rubric accompanies the lesson Introduction to Negative Numbers.
Geometric Proofs Proof - A trapezoid is isosceles if and only if the two base angles are equal. An isosceles trapezoid is a trapezoid where the non-parallel sides are equal in length.