Sal defines ratios. Then he shows how to write ratios three different ways. This concept is then demonstrated with four examples for finding quantities by using ratios.

The instructor continues to build ratio problem-solving skills algebraically. The two examples are very involved but are thoroughly explained using algebraic steps.

Here is a complete and clear demonstration of the process needed to factor a trinomial with a non-1 leading coefficient. Sal uses various colors and provides working examples while he factors the simple trinomial. This video would be...

Teach your robot some new tricks. The second video in the Crash Course Artificial Intelligence series focuses on supervised learning. Viewers examine historical approaches to supervised learning, such as the perceptron, and see how...

Let the machines do what they do best. The 37th installment of the Crash Course Statistics series focuses on unsupervised machine learning. It describes two methods, k-means and hierarchical clustering, and provides examples for each.

Sometimes you'll need to solve an equation with multiple variables on each side. This step-by-step tutorial will show you how to set your equation to 0, factor out the GCF, simplify, write your answers as a set, then plug and chug to...

There are four terms in this polynomial. Try to factor it by grouping the terms. Confused? Try to get four terms into the product of two binomials? Still confused? Watch the instructor as she goes through the steps to group and regroup...

How do you know that a binomial can be factored using the difference of squares? First try finding the greatest common factor and pulling that out. Then take a look at what is left. Are the coefficients perfect squares? Then it could be...

When Curious George invites a group of dogs home from the Dog Show, he has to figure out a way to sort them so that he can count them correctly. After watching the video, students learn about classifying objects that have common...

This video will help children learn to count and group rocks withPeg and Cat. Peg and Cat share rocks to build a spaceship. Includes a "Teacher Feature" which demonstrates how one teacher used this resource in her classroom. [1:02]

Employees explain how they use the mathematical concept of grouping and sorting every day in their jobs in the logistics and transportation industries.