Lesson 4 — Ethereum Blockchain

Ethereum expanded blockchain use beyond simple transfers by introducing smart contracts. A smart contract is code deployed on a blockchain that can execute rules automatically. This allows developers to build decentralized applications, tokens, DeFi protocols, NFT systems, DAOs, and many other blockchain-based tools.

This lesson introduces Ethereum as a programmable blockchain. Students learn that Ethereum is not only a currency network; it is an infrastructure layer for decentralized computation. Users interact with this infrastructure through wallets, gas fees, contract approvals, and transactions.

Gas is an important concept. Every transaction or smart contract interaction requires computational resources, and gas fees are paid to process that activity. When network demand is high, fees can rise. Understanding gas helps users avoid confusion and operational mistakes.

Students also learn that smart contracts create both opportunity and risk. Code can automate financial logic, but code can also contain bugs. Users can approve unsafe contracts, interact with malicious protocols, or misunderstand what they are signing.

Ethereum is central to crypto education because many DeFi, NFT, token, and on-chain data concepts depend on it. Understanding Ethereum helps students understand the wider blockchain ecosystem more professionally.

1. Explain what a smart contract is.
2. Find one Ethereum transaction and identify the gas fee.
3. List three types of applications built on Ethereum or Ethereum-like networks.
4. Write two risks of interacting with smart contracts.