You know the "states of matter", right? Solid, liquid, gas... and plasma? Test your knowledge with this Tetris-like game by sorting the falling objects into the appropriate bins. Be careful though: you're only allowed a few mistakes, and each level will be faster than the last.

What's a plasma? Where can you find plasmas? Plasmas are gases where some electrons have been knocked off the atoms. That can make them glow, as the electrons reconnect back with the atoms and release energy as light. Our Sun is a giant plasma ball of gas. Closer to home, the Northern Lights are also another example of a plasma in Nature, as well as the gas glowing inside a fluorescent light bulb.