Tower of Epiphany on Scratch:
Think Like a Coder – Tower of Epiphany – TedEd video:
Videos on LEDs:
a non-profit library of millions of free books, movies, software, music, websites, and more.
This site also has the “Wayback Machine” (near the top of the page) where you can see how a website has changed over the years – just enter the web address!