Blockchain Technology – SS2 Digital Technologies Lesson Note (Third Term)

Blockchain is a digital ledger, or record book, that is shared across thousands of computers. Information is stored in blocks that are linked in a chain, and once it is added it is almost impossible to change. This lets people prove that records are true without a middleman such as a bank.

Behavioural objectives

By the end of the lesson, students should be able to:

• explain what blockchain is, using the shared diary idea;
• describe blocks, chains and hashes and say why a blockchain is called “immutable”;
• explain what cryptocurrency is and what “mining” means;
• give three uses of blockchain beyond money;
• compare blockchain with a traditional system such as a bank, and state its advantages and challenges.

What is blockchain?

Imagine you and your friends have a diary. Every time someone spends money, you write it in the diary. There are two rules:

• Everyone has a copy of the same diary.
• If one person tries to erase a page or change a number, their diary will not match everyone else’s, and the group will know they are cheating.

Blockchain works like this shared diary. It is a digital “ledger” (a record book) that is shared across thousands of computers. Once information is added, it is almost impossible to change. It proves the truth without needing a middleman like a bank or a boss.

How does blockchain work? (Blocks and chains)

A blockchain is made of two parts:

1. The blocks: Think of these as pages in our diary. Each block contains a list of data (like who sent money to whom).
2. The chain: Each page is “glued” to the one before it using a special digital fingerprint called a hash. If you change even one letter on Page 1, the fingerprint changes, and the “chain” to Page 2 breaks.

Teacher’s note: This is why a blockchain is called “immutable”. Immutable is just a fancy word for “it cannot be changed.”

What is cryptocurrency?

The most famous use of blockchain is cryptocurrency (like Bitcoin or Ethereum). It is digital money that does not belong to any country or bank.

• Traditional money (naira): Controlled by the Central Bank. If their system goes down, you cannot pay.
• Cryptocurrency: Controlled by the blockchain. It works 24/7, and nobody can “freeze” your account without your private key.

How is cryptocurrency “mined”?

You might hear people talk about “Bitcoin mining”. It has nothing to do with digging in the ground. Powerful computers work hard to solve math problems that verify the next “block” in the chain. As a reward for this work, they get new coins.

How else is blockchain used? Uses beyond finance

Blockchain is used for more than Bitcoin. Its real strength is keeping records safe. Here are three other uses.

Voting systems

Imagine voting for the Head Boy or even the President on a blockchain. Because the records cannot be edited or deleted, it would be very hard to “stuff” the ballot box or change the results.

Land ownership (real estate)

In many places, people fight over land because paper documents get lost or forged. If land titles are put on a blockchain, everyone can see exactly who bought the land and when. You cannot sell the same land to two different people.

Supply chain (tracking goods)

Have you ever wondered if the “organic honey” you bought is actually real? Companies use blockchain to track a product from the farm to the store. You can scan a code and see exactly which farm your food came from.

How does blockchain compare with traditional systems?

What are the advantages and challenges of blockchain?

The advantages

• Security: Almost impossible to hack.
• No middleman: You do not pay high bank fees to send money.

The challenges

• Energy: Mining coins uses a lot of electricity.
• Irreversible: If you lose your “private key” (your password), your money is gone forever. There is no “Forgot Password” button.

Evaluation

1. In your own words, explain why a “hash” is like a digital fingerprint.
2. If you were the Minister of Education, how could you use blockchain to stop people from using “fake” WAEC certificates?
3. Activity: Draw a chain of three squares (blocks). Inside each block, write a simple transaction (e.g., “Ade gave 5 tokens to Joy”). Draw an arrow connecting them to show the “chain.”

Assignment

Choose one use of blockchain from this lesson (voting, land ownership or supply chain). Write a short paragraph explaining how blockchain records, which cannot be changed, help in that area.