The Maker Show: Episode 1 - Intro to Electronics

The "Hello World" of electronics is a blinking LED. But what do you do after that? In this episode of the Maker Show, we will use the Arduino to introduce a few new ways to work with your blinking LED from inputs with buttons and potentiometers to viewing input in the serial monitor.
[00:00] - Introduction
[00:26] - Hello World...or blinking LED
[03:15] - Dimming an LED with Analog
[07:01] - Digital Input with a Button
[09:51] - Analog Input with a Potentiometer
[15:23] - Conclusion
Another interesting video. I'd like to have known more about the potentiometer example, in what regards electricity. Why 50k, for example? or why is the value between 0-1024? Is this value arbitrary? And if the Led is analog, I assume 0-255 is a discretization of some voltage?
Nothing special about the 50k resistor (except it was what I had on hand when shooting the video). The analogRead will give you a values between 0 and 1023. This represents the a value from 0 to 5v...so it's not entirely arbitrary. When the voltage is 0, the value is 0. When the voltage is 5v, you will have 1023. If you incorrectly connected this to a 3.3v pin, you would only get up to a value around 670 - 680.
On the other hand, analogWrite only takes values between 0 and 255. 0 being always off and 255 being always on. Otherwise it is a pulse is at a regular frequency (depending on the speed of the pin). This is PWM. To be clear, the LED is digital. Connecting it to a PWM port allows you to blink it on and off in a frequency that is more off than on (less than 128) or more on than off (greater than 128) and allowing perception to take over on the "brightness" of the LED.
A great place to read more about potentiometers and Arduino is here: https://www.arduino.cc/en/Tutorial/AnalogInput