# Khan Academy

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### Computer science

Computer Science7th - College | Online class

Learn select topics from computer science – algorithms (how we solve common problems in computer science and measure the efficiency of our solutions), cryptography (how we protect secret...

### Conceptual and Performance art

Performance ArtsHigh School - College | Online class

Does art need to be a physical thing, an object made of stone or canvas? Could art be an idea enacted, a process, or an environment inhabited and transformed?

### Congruence

6th - High School | Online classTwo figures are congruent if you can go from one to another through some combination of translations, reflections and rotations. In this tutorial, we’ll really internalize this by working through...

### Conic sections

Conic Sections8th - High School | Online class

Sal introduces the four conic sections and shows how they are derived by intersecting planes with cones in certain ways.

### Conjugated systems and pericyclic reactions

Online classMolecules with conjugation can undergo some interesting and useful reactions! We will be learning about the Diels-Alder reaction, including how to predict the stereochemistry and regiochemistry of...

### Consumer and producer surplus

Online classMany times, the equilibrium price is lower than the highest price some folks are willing to pay. For all consumers, this is called consumer surplus. Similarly, the price might be higher than the...

### Cosmology and astronomy

Astronomy7th - College | Online class

The Earth is huge, but it is tiny compared to the Sun (which is super huge). But the Sun is tiny compared to the solar system which is tiny compared to the distance to the next star. Oh, did we...

### Counting

Numbers & CountingPre-K - 1st | Online class

Counting small numbers. Learn to count from 0 to 20. Sal counts squirrels and horses. Practice counting up to 10 objects. Learn how to count without making mistakes. Find 1 more or 1 less than a...

### Course materials

Online classThese syllabi and sample discussion questions are for the use of instructors who are encouraged to build on and adapt them for their own classes. They can also be used by individual learners...

### Critical analysis and reasoning skills practice questions

Online classAll content in “Critical analysis and reasoning skills practice questions”

### Current economics

EconomicsHigh School - College | Online class

Unemployment is a key metric for judging the health of an economy (and even political stability). This tutorial is a primer on what it is and how it’s measured (which you might find surprising).

### Data and modeling

Online classWhen we display data on scatter plots, we often see trends. Sometimes these trends are linear, meaning that the data roughly follows the path of a line.

### Data and statistics

Statistics & ProbabilityHigh School - College | Online class

In statistics, we try to make sense of the world by collecting, organizing, analyzing, and presenting large amounts of data. For example, you may survey your friends about what tv show is most...

### Data sufficiency

Online classSal works through the 155 data sufficiency questions in chapter 6 of the the 11th edition of the official GMAC GMAT Review (ISBN Number: 0-9765709-0-4 published in 2005)

### Derivatives of multivariable functions

Derivatives & Differential CalculusHigh School - College | Online class

What does it mean to take the derivative of a function whose input lives in multiple dimensions? What about when its output is a vector? Here we go over many different ways to extend the idea of a...

### Descriptive statistics

Statistics & ProbabilityCollege | Online class

This is the foundational tutorial for the rest of statistics. We start thinking about how you can represent a set of numbers with one number that somehow represents the “center”. We then talk about...

### Differential calculus

Differential Equations9th - College | Online class

Missions recommend what to learn next, help you remember what you’ve learned by mixing skills, and save your progress.

### Differential equations

Differential EquationsCollege | Online class

How is a differential equation different from a regular one? Well, the solution is a function (or a class of functions), not a number. How do you like me now (that is what the differential equation...

### Discoveries and projects

Online classhow would you know which way is north if you had no reference? Can the direction of stroke alone tell you this? Are you sure?

### DNA as the genetic material

GeneticsHigh School - College | Online class

What exactly is DNA? This seemingly simple polymer, made up of just four different types of monomers, serves as the genetic material for all living organisms. For example, your DNA provides...

### Doodling in Math and more

Online classYou’re feeling spirally today, and math class today is taking place in greenhouse #3…

### Early abstraction: Fauvism, Expressionism, and Cubism

Online classLes Fauves (the wild beasts) used color the way most artists use line, to define form in space. From these brilliant early experiments, Henri Matisse went on to create some of the most daring and...