Too Long; Didn't Read
As inspired by <a href="http://rubykoans.com/" target="_blank">Ruby Koans</a>, <a href="https://soliditykoans.org/" target="_blank">Solidity Koans</a> guides you through simple, bite-sized programming exercises to learn Solidity the gentle way. The goal is to learn the Solidity language, syntax, structure, and how to create secure and gas-efficient smart contracts. It starts off with the basics and slowly guides you through the inner workings of the EVM, through assembly code and security considerations.