# Khan Academy

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### Light waves

Light & SoundHigh School - College | Online class

In these videos and articles you’ll learn about the different categories of the electromagnetic spectrum; radio waves, microwaves, infrared, visible, ultraviolet, x-ray, and gamma ray. You’ll also...

### Linear algebra

Linear AlgebraCollege | Online class

Have you ever wondered what the difference is between speed and velocity? Ever try to visualize in four dimensions or six or seven? Linear algebra describes things in two dimensions, but many of...

### Linear equations and functions

Online classWhen you walk at a constant rate, the relationship between the distance you’ve walked and the time you’ve spent walking is proportional. In this tutorial, we learn about proportional relationships...

### Linear equations and functions word problems

Online classLinear equations word problems: earnings Sal finds the slope of a linear relationship between the number of work hours and the money earned. He then interprets what this slope means in that context.

### Linear equations and inequalities

Online classNow we’ll introduce you to the most fundamental ideas of what equations mean and how to solve them. We’ll then do a bunch of examples to make sure you’re comfortable with things like 3x – 7 = 8. So...

### Lines

4th - 9th | Online classLet’s draw points, lines, line segments, and rays. We’ll also think about perpendicular and parallel lines and identify these in two-dimensional figures. Common Core Standard: 4.G.A.1

### Lymphatic system physiology

Anatomy & PhysiologyCollege | Online class

Your heart pumps roughly 20 L of blood throughout the day to your tissues. The plasma component of blood (not containing blood cells) leaks out through capillaries (the tiniest of blood vessels)...

### Macroeconomics

MacroeconomicsHigh School - College | Online class

Macroeconomics Explore Table of contents Topics GDP: Measuring national income Inflation – measuring the cost of living Aggregate demand and aggregate supply The monetary system Income and...

### Macromolecules

Online classThere’s an old saying, “You are what you eat.” In some senses, this is literally true! When we eat food, we take in the large biological molecules found in the food, including carbohydrates,...

### Magnetic forces, magnetic fields, and Faraday's law

Electricity & Magnetism9th - College | Online class

Magnetic fields are extremely useful. The magnetic field of the Earth shields us from harmful radiation from the Sun, magnetic fields allow us to diagnose medical problems using an MRI, and...

### Mannerism

Online classThe Mannerist style developed in the courts of the Italian elite. It built on Renaissance naturalism but distorts and deceives to delight its highly educated audience.

### Masterpieces old and new

Online classPossibly the most iconic of all symphonies, “Beethoven’s 5th” is instantly recognizable by its dramatic opening motive. Learn how this rhythmic and melodic idea permeates the entire work, holding...

### Math for fun and glory

Math7th - College | Online class

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

### Matrices

Online classLearn what matrices are and about their various uses: solving systems of equations, transforming shapes and vectors, and representing real-world situations. Learn how to add, subtract, and multiply...

### Matrix transformations

Online classPeople have been telling you forever that linear algebra and matrices are useful for modeling, simulations and computer graphics, but it has been a little non-obvious. This tutorial will start to...

### Measurement

Online classArea is how we thinking about how much space something takes in two dimensions such as comparing how much land one property takes up versus another. In this tutorial, we’ll take a conceptual look...

### Measurement and data

Online classWhen we measure anything, we do it in human-defined ‘units’. Different units were defined in different places and for different scales. The two most common are U.S. customary units and metric...

### Measurement and data

Online classIf you think about it, we measure almost everything: time, distance, size, weight, volume, etc. Every THING can be measured. The question is, what unit of measurement is used and how is that unit...

### Measurement and data

MeasurementKindergarten - 3rd | Online class

Learn how to measure length, tell time, count money, and make graphs.

### Measurement and geometry

Geometry2nd - 4th | Online class

In 2nd grade, you learned to measure lengths. Now we can measure the length around the edge of an object (perimeter) and how much “space” something takes up on a flat surface (area).

### Medieval Europe

Middle Ages / Medieval Period7th - College | Online class

The Middle Ages lasted 1000 years. Learn how manuscripts were made, how medieval calendars worked, and how Christ’s life was represented.

### Medieval period

Art HistoryHigh School - College | Online class

Medieval Period (c. 900-1517 C.E.) The Fatimids (909-1171) ruled north Africa, and parts of Syria and the Seljuqs contolled eastern Islamic lands and eventually Iran, Iraq and much of Anatolia.

### Meet the chemistry professional

Online classWe’ve invited professionals from all kinds of careers to share their stories. What do all these people have in common? They all studied chemistry! Find out how chemistry can be used in everything...