basics
soldering
led arrays, multiplexing, shift registers
lcds and oleds
tools and resources
circuit design apps
Octopart
“the electronic part search engine”
PhET educational simulations
courses, tutorial lists, books
Ultimate Electronics
free online textbook, maybe with interactive diagrams? still in development?
From Nand to Tetris: Building a Modern Computer From First Principles
(higher level - going from building logic circuits to building operating systems - highly recced course for CS)
part 1 (the hardware half) on coursera:
Build a Modern Computer from First Principles: From Nand to Tetris (Project-Centered Course)
Tutorials - Circuits 101 | CircuitBread
Tutorials - Microcontroller Basics | CircuitBread
Learn with 34 video tutorials to program your Arduino (arduino-tutorials.net)
Learn Circuits | Tinkercad
Ultimate Guide to the Arduino - Circuit Basics
https://community.element14.com/learn/learning-center/essentials/
lessons and tutorials