Using the teaching demos in class

Demo 1: Blockchain

Links are on the platforms page. A suggested order:

1. Hash. Change one character in the input and watch the hash change completely — determinism and the avalanche effect.
2. Block. Introduce the nonce and “mining”; have students click Mine to see leading zeros appear — proof of work.
3. Chain. Edit data in a middle block and watch all later blocks turn red — tampering cost grows with chain length.
4. Distributed. Open several node views, tamper on one, and compare with others — how majority consensus detects a tampered replica.
5. Tokens & transactions. Replace block contents with transfers to show the ledger–balance relationship.

Demo 2: Public/private keys and signatures

1. Key pair. Generate a pair; the public key can be shared, the private key must stay secret.
2. Signature. Sign a message with the private key and verify with the public key; verification fails after editing the message.
3. Transaction. Replace the message with a transfer to show that the private key decides who can spend.
4. Back to the chain. Put the signed transaction into a Demo 1 block to connect the whole picture.