Instructional Video4:38
Khan Academy

Rhombus Diagonals, Quadrilaterals, Geometry

For Students 9th - 10th
Delving into proof that the diagonals of a rhombus are perpendicular to each other, this lecture evaluates the angles and sides of this figure. It would serve as a great test preparation activity.
Instructional Video17:37
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Flipped Math

Conditions for Rectangles, Rhombuses and Squares

For Students 9th - 12th Standards
Here's a special lesson about some special parallelograms. The fifth of seven parts in the Geometry - Quadrilaterals and Polygons unit focuses on the conditions for rectangles, rhombuses, and squares. Young mathematicians use these...
Instructional Video
Khan Academy

Khan Academy: Triangles: Another Pythagorean Theorem Proof

For Students 9th - 10th Standards
Students explore the Pythagorean Theorem by exploring a visual proof of the Theorem as they watch a video tutorial.
Instructional Video
Khan Academy

Khan Academy: Geometry: Right Triangles Inscribed in Circles (Proof)

For Students 9th - 10th Standards
This video tutorial [5:35] explains that if the diameter of a circle is one of the sides of a triangle inscribed in the circle then the triangle is a right triangle. This video also appears in the strand Geometry: Circles.
Instructional Video
Sophia Learning

Sophia: Pythagorean Theorem Proof

For Students 9th - 10th Standards
Prove the Pythagorean theorem and take a quiz to assess learning.
Instructional Video
Sophia Learning

Sophia: Cpctc (Corresponding Parts of Congruent Triangles)

For Students 9th - 10th Standards
Complete a multiple step proof to determine if two triangles are congruent. Take quiz to check for understanding.