Class 8, The Bitcoin Blockchain.

A block chain is a transaction database shared by all nodes participating in a system based on the Bitcoin protocol. A full copy of a currency's block chain contains every transaction ever executed in the currency. With this information, one can find out how much value belonged to each address at any point in history. Every block contains a hash of the previous block. This has the effect of creating a chain of blocks from the genesis block  to the current block. 

As a new user, you can get started with Bitcoin without understanding the technical details. Once you have installed a Bitcoin wallet on your computer or mobile phone, it will generate your first Bitcoin address and you can create more whenever you need one. You can disclose your addresses to your friends so that they can pay you or vice versa. In fact, this is pretty similar to how email works, except that Bitcoin addresses should only be used once.

We should consider Bitcoin to be an experiment. Like any good experiment, we gain valuable knowledge and design the next experiment. There are many other Blockchains that perform the essential functions as bitcoin without the inefficiency of mining. Some of these include Bitshares (proof of stake) and Maidsafe (proof of resource). Another advancement to watch is something called Curiosumé (The Ingenesist Project) which turns your resume into cryptography allowing people to build smart keys that open smart contracts on smart block chains. I believe that this is the "intuition" that everyone in the engineering professions senses ought to happen with this great technology.