Curated Video
Space station supplies launched, 2nd shipment in 2 days
A load of space station supplies rocketed into orbit from Virginia on Saturday, the second shipment in two days.
Curated Video
Unmanned cargo rocket takes off for ISS to deliver supplies
An unmanned cargo rocket took off early on Saturday from the US State of Virginia bound for the International Space Station to deliver supplies.
Curated Video
UK guide fears for climbers missing in Pakistan
A British mountain guide who knows the missing British climber Tom Ballard, told The Associated Press on Monday that he was beginning to have "negative thoughts" about his fate, and that of his Italian partner, Daniele Nardi.
Curated Video
India Says 20 Soldiers Have Been Killed At Disputed Border With China
India initially reported three deaths after skirmishes with Chinese troops.
Sherman Grinberg Film Library
Animated illustration of Soviet Union's 1957 Sputnik mission
Animation throughout: nose cone of rocket opens to free Sputnik satellite, which unfolds and moves away from rocket / Sputnik in orbit around Earth / trajectory of Sputnik's orbit around Earth / from Greatest Headlines of the Century series
Curated OER
SAT Prep: Test 4 Section 4 Part 2
Problems 7-11, which involve both geometry and algebra problems, allow students to practice transitioning between skills. Sal takes time to explain the process of each problem so that students will understand the test strategies as well...
Khan Academy
SAT Prep: Test 5 Section 9 Part 1
Reasoning through the methodology of a new set of problems from page 679 of The Official SAT Study Guide, Sal shows students how to find the ins and outs of increasingly difficult math problems. He advises them to thoroughly think over...
Khan Academy
SAT Prep: Test 5 Section 7 Part 2
Sal teaches the importance of careful reading and canceling out all possible units as he solves problems 6-9 on the practice SAT. Students who have a hard time deciphering word problems would benefit from this video. Sal's annotation and...
Corbett Maths
Pythagoras Rectangles and Isosceles Triangles
When does the Pythagorean Theorem come in handy? An intriguing video uses the Pythagorean Theorem to solve problems other than simply finding the length of a side of a right triangle. Pupils find the diagonal of a rectangle and the...
CK-12 Foundation
Altitudes: Examples
Find the location of altitudes—from any elevation! The video presents the definition of an altitude of a triangle. By drawing examples, the segment of a larger geometry playlist highlights the location of altitudes of various triangle...
CK-12 Foundation
Inscribed Similar Triangles: Lesson
Create similar triangles with a little altitude. A section of an extensive playlist on basic geometry discusses how an altitude of a right triangle creates similar triangles. Using the theorem, the presentation finds unknown side...
TED-Ed
Why is Mount Everest so Tall?
Many years ago, when the Indian plate collided into the Eurasian plate, the highest mountain on Earth was formed. But what gives Mount Everest its shape? Watch an informative video to learn what factors make the...
Khan Academy
Khan Academy: Geometry: Common Orthocenter and Centroid
Proves that if the orthocenter and centroid are the same point in a triangle then the triangle is a right triangle. [6:25]
Khan Academy
Khan Academy: Geometry: Euler Line
Demonstrates that the circumcenter, orthocenter, and centroid of a triangle all lie on a line called an Euler line. [6:12]
Science Friday Initiative
Science Friday: Mount Everest Still Holds Mysteries for Scientists
Hear about several scientists' quest to re-measure the altitude of Mount Everest's peak, a statistic still under dispute.
Sophia Learning
Sophia: Triangle Height
In this video tutorial, explore how to determine the height of obtuse, acute, and right triangles. Take a quiz to assess learning. [6:15]
Khan Academy
Khan Academy: Geometry: Euler's Line Proof
Proves that the circumcenter, orthocenter, and centroid all lie on the same line, the Euler line. Proof relies on understanding of properties of similar triangles and properties of special parts of a triangle. [9:50]
Khan Academy
Khan Academy: Proof: Triangle Altitudes Are Concurrent (Orthocenter)
Showing that any triangle can be the medial triangle for some larger triangle. Using this to show that the altitudes of a triangle are concurrent (at the orthocenter).
Khan Academy
Khan Academy: Common Orthocenter and Centroid
Showing that a triangle with the same point as the orthocenter and centroid is equilateral.
Sophia Learning
Sophia: Triangle Height: Lesson 3
This lesson will demonstrate how to locate the height in an obtuse, right, and acute triangle. It is 3 of 5 in the series titled "Triangle Height."