Rounding is an essential skill that must be used throughout the study of mathematics. This Khan Academy video is the first in a series of three. It shows how to round the number 24,259 to the nearest hundred, using a number line.

This is the second in a series of three Khan Academy videos on rounding whole numbers. Students watch Sal Khan round the number 423,275 to the nearest thousand by looking at the number in the hundreds place. If it is five or higher, you...

To subtract two polynomials, Sal demonstrates that you add the opposite of the second term, and then combine like terms to solve. How do you find an opposite term? Multiply the polynomial by -1. This video is very clearly explained and...

Adding two polynomials begins with simplifying when possible. Sal demonstrates the process he uses to combine like terms and explains why the process works. This video would be great for those who need a quick refresher.

History comes alive in this engaging video, which artfully sets up the first steps of the French Revolution. Students will relate to the idea of nobility living in luxury while 98% of the French citizens went without wealth or rights....

A large amount of ice exists on the moon making colonization that much easier. The video discusses the creation of the moon and the materials and features on it. It also discusses the reasoning behind our moon being just one of...

A massive star has a mass greater than nine times that of our sun. Sal focuses on the fusion and chemical reactions that take place during the lifecycle of a massive star. He clearly explains the gravitational pull to the chemical...

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.

Sal reviews absolute value equations by taking viewers through a careful and deliberate problem-solving process. Those who didn't thoroughly understand absolute value during class will appreciate Sal's steady and straightforward...

Show your students this presentation to help them understand how to add fractions with like denominators. Sal adds 3/15 to 7/15 and then simplifies his answer. He uses drawings and multiple colors to show the actual process.

In this video, Sal shows how the sine and cosine of an angle are defined on the unit circle. He inscribes a 30-60-90 triangle in the unit circle and explains how to use SOH-CAH-TOA to find the circle's coordinates.

Sal makes a relatable comparison for pupils to understand the universe's relative size. The progression from a man's size to a galaxy's size is explained in terms of each object relative to the next. The multiple objects we can process...

The details of nephron structure and the importance of renal tubules in osmosis, reabsorption, and secretion of solutes, and the related concentration of the final filtrate.

This video, the first in a series on the Pythagorean theorem, introduces the formula for discovering the measurement of a side of a right triangle. The material is introduced and explained in a straightforward and easy-to-understand...

Here is a special form of a sum of cubes problem, where students use algebraic multiplication to rewrite each term in expanded form. Sal gives an example before solving the problem to show the process that he will use to determine the...

Math and real life converge in this video, which details the process of death probability in terms of life insurance. Although your students are likely years away from considering life insurance, it's beneficial to illustrate probability...

This video provides a reasonable explanation for blossoming mathematicians, explaining the difference between average and central tendency, as well as arithmetic mean, median, and mode. Those who haven't grasped these concepts in algebra...

"Just to get the point drilled into your head," Sal continues his lecture on factoring quadratic expressions, focusing on special products. He works to instill the problem-solving skills necessary to factor in equations quickly and...

Sal trades his tablet for an Excel spreadsheet in this video, which covers fitting data to a line. Using a word problem about median income, he not only solves the problem but also demonstrates how to use scatter plots and Excel tools in...

Here is an equation in which the first step is to use the distributive property to remove the parenthesis. Then, it is solved for the variables. Since variables are on both sides of the equation, it is important to verify the answer by...

1-bromo-1-fluoroethane is the first example of stereoisomers that exhibit different chemical properties and polarize light in distinct ways. An informative video focuses on how to differentiate between enantiomers using the...

Building on the previous video, Sal further explains different situations and the reactions that would occur in each.