Lesson 1 - Introduction to Blockchain & Decentralization.
Blockchain Technology
Section outline
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Lesson 1: Introduction to Blockchain & Decentralization establishes the foundational shift from centralized systems (banks, governments, platforms that create single points of failure) to decentralized alternatives built on Distributed Ledger Technology (DLT). You will learn how cryptographic hashing creates immutability—linking blocks together so any tampering becomes instantly detectable—and how peer-to-peer (P2P) networks enable consensus without any middleman authority. You will also tackle the Byzantine Generals Problem, the classic thought experiment that explains why coordinating trust among strangers who may be malicious is so difficult, and how blockchain's combination of cryptography, consensus, and economic incentives finally solved it. Through a hands-on "chain" exercise and a video-based trivia quiz, you will then complete a five-question quiz and a reflective journal titled "My Trust Model," where you identify friction points caused by centralized trust in your own community or social business.
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Students mustMark as done
From centralization to decentralization.pptx by Jovan Karamachoski
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Students mustMark as done
Cryptographic hashing - the engine of immutability.pptx by Jovan Karamachoski
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Let's See Hashing in Action
Go to the following link:
https://xorbin.com/tools/sha256-hash-calculator
(or any SHA-256 online tool)Try these steps:
- Type your name → Get hash
- Type your name with a period at the end → Get hash
- Compare – completely different, right?
- Try sending a friend your hash – they type your name and get the same!
This is how blockchain verifies without revealing data.
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Build Your Own Immutable Chain
A short group task where participants use a text field (paper, card) to pass a message, each adding a new line and then hashing the entire message (conceptually) to visualize immutability.
Time: 15 minutes
Setup (in groups of 4-5):
- Each group gets a stack of index cards (or a shared digital document)
- Each person will add ONE card/entry to the chain
- We'll simulate hashing (simplified for the exercise)
Simplified "Hash" Rule:
A hash = first 3 letters of the message + number of characters
Example: "We fund the garden" → "We 16" (in reality, real hashes are complex) -
Students mustMark as done
Peer-to-peer networks.pptx by Jovan Karamachoski
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Students mustMark as done
Video: "What is a Peer-to-Peer Network?" – Blockchain at Berkeley / Simply Explained (5 minutes)
Link:
As you watch, note answers to these questions:
- What is the main difference between client-server and P2P?
- How does a P2P network stay running if nodes leave?
- What happens to data in a P2P network if one node is corrupted?
If the video link doesn't work:
Alternative Video: "Blockchain 101 – A Visual Demo" by Anders Brownworth (first 7 minutes)
Link :
or Search on YouTube: "Peer to Peer Networks Explained Simply"
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Students mustMark as done
Trustless systems & the Byzantine generals problem.pptx by Jovan Karamachoski
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Question:
"Think of a situation in your volunteer work or community where trust is currently required – but that trust is sometimes broken, expensive, or opaque. Could a trustless (trust-minimized) system help?"Examples to consider:
- Donation tracking
- Volunteer hour verification
- Community voting
- Shared resource allocation
- Grant distribution
Share with a partner, then we'll hear 2-3 examples.
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For Deeper Understanding
Original Paper (very technical):
"The Byzantine Generals Problem" – Lamport, Shostak, Pease (1982)
Link: https://lamport.azurewebsites.net/pubs/byz.pdf (Read just the abstract and introduction)Accessible Explanation:
"The Byzantine Generals Problem – Simply Explained" – Various YouTubers (search)Bitcoin Whitepaper Reference:
Satoshi Nakamoto's "Bitcoin: A Peer-to-Peer Electronic Cash System" – Section 2
Link: https://bitcoin.org/bitcoin.pdf -
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Shape the Future.
Mint the Change.
