BLK103 · Smart Contracts and Decentralized Applications

Categories: Emerging Technology
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About Course

Write, deploy and test your first Solidity smart contract in the browser, and learn how decentralized applications connect a web interface to contract logic on a test network.

Build · 6 hours · 4 lessons, a lab, an assessed assignment and a portfolio piece

Who it is for

Developers, technical analysts and curious business professionals who want to build and reason about simple smart contracts.

Prerequisites

BLK102; basic familiarity with any programming language is recommended.

What you will be able to do

  • Explain what a smart contract is, how it is executed by the Ethereum Virtual Machine and why gas exists
  • Write a Solidity contract with state variables, functions, events, modifiers and access control
  • Deploy and test a contract in the Remix VM and, optionally, on the Sepolia test network
  • Describe the architecture of a decentralized application, including wallets, RPC providers and off-chain storage

Lessons

  • Lesson 1 · What smart contracts are and how they run
  • Lesson 2 · Solidity essentials
  • Lesson 3 · From contract to decentralized application
  • Lesson 4 · Lab and assignment

Lab: Build a supplier order-tracking contract

You write a contract that lets a buyer create purchase orders and a supplier mark them shipped, emitting an event at each step. You deploy it to the in-browser Remix VM, which simulates a blockchain with test accounts and no real value. You test permissions by switching accounts and confirming that unauthorized actions are rejected.

Free tools: Remix IDE (browser) with the built-in Remix VM; optional Sepolia test network

Assessed assignment

Extend the lab contract so an order moves through Created, Shipped and Delivered, and only the correct party can trigger each step. Add an event for every change and a function that returns the status of an order. Write at least five manual test cases in Remix (including two that should fail) and record the results in a table. Finish with a half-page note explaining the gas cost of each function and one design change that would reduce it.

Criterion Weight What excellent work looks like
Contract correctness 35% Compiles without warnings, enforces the status sequence and rejects out-of-order or unauthorized actions.
Events and readability 20% Uses clear names, comments and events that an off-chain app could easily consume.
Testing evidence 30% Test table covers success and failure paths with expected and actual results and screenshots or logs.
Gas analysis 15% Reports gas used per function and proposes a realistic optimization with reasoning.

Portfolio piece

A tested Solidity order-tracking contract with a test log and gas analysis, saved to a public or private GitHub repository.

Self-paced, 12-month access. Questions are answered in writing through the student panel. A completion record is issued when you finish the course.

Next step

Continue with BLK104 · Tokens, Digital Assets and Web3 Use Cases · 6 hours · $42.00

Continue to the next course

Prefer the whole program? Program in Blockchain, Web3 & Digital Identity · $277.00 (10% less than buying the courses separately)

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What Will You Learn?

  • Explain what a smart contract is, how it is executed by the Ethereum Virtual Machine and why gas exists
  • Write a Solidity contract with state variables, functions, events, modifiers and access control
  • Deploy and test a contract in the Remix VM and, optionally, on the Sepolia test network
  • Describe the architecture of a decentralized application, including wallets, RPC providers and off-chain storage

Course Content

BLK103 · Smart Contracts and Decentralized Applications (6 h)
Write, deploy and test your first Solidity smart contract in the browser, and learn how decentralized applications connect a web interface to contract logic on a test network.

  • Lesson 1 · What smart contracts are and how they run
  • Lesson 2 · Solidity essentials
  • Lesson 3 · From contract to decentralized application
  • Lesson 4 · Lab and assignment
  • BLK103 Assessment · Smart Contracts and Decentralized Applications
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