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Smart Contract-based Exam System

This project implements a basic exam system using a Solidity smart contract. It allows a teacher to add questions and correct answers to an exam, and students can submit their answers to get automatically graded. Students can also view all the stored questions at once.

Features

• Teacher Functions:

  • Add questions to the exam with correct answers.
  • Manage questions stored on the blockchain.

• Student Functions:

  • Submit answers for grading.
  • View their scores.
  • Retrieve all the exam questions at once.

Contract Overview

Structs

• Question: Represents a question in the exam. It contains:
  • questionText: The text of the question.
  • correctAnswer: The correct answer for the question.

Mappings

• scores: Stores the scores of students, mapped by their address.

Variables

• questions: An array of Question structs to store all the exam questions.
• teacher: The address of the teacher who deployed the contract.

Functions

• addQuestion(string memory questionText, string memory correctAnswer) public onlyTeacher:

  • Adds a new question with the corresponding correct answer.
  • Can only be called by the teacher.

• submitAnswers(string[] memory answers) public:

  • Submits the student's answers for grading.
  • Compares the student's answers to the correct answers stored on the blockchain and calculates their score.

• getScore() public view returns (uint):

  • Returns the score of the student calling the function.

• getAllQuestions() public view returns (string[] memory):

  • Returns an array containing all the question texts in the exam.

Prerequisites

• Solidity: The smart contract is written in Solidity (version 0.8.0 or above).
• Ethereum Wallet: To interact with the deployed contract, you'll need an Ethereum wallet like MetaMask.
• Ethereum Testnet: Deploy the contract on an Ethereum-compatible testnet like Rinkeby, Goerli, or Arbitrum testnet.

Deployment and Usage Instructions

1. Deploy the Contract

1. Open Remix IDE:

   • Visit Remix IDE.
   • Create a new file named Exam.sol and paste the provided Solidity code.

2. Compile the Contract:

   • Navigate to the "Solidity Compiler" tab.
   • Choose compiler version 0.8.0 or higher.
   • Click "Compile Exam.sol".

3. Deploy the Contract:

   • Go to the "Deploy & Run Transactions" tab.
   • Select the Exam contract from the dropdown.
   • Ensure that the environment is set to "Injected Web3" to connect to MetaMask.
   • Click "Deploy" and confirm the transaction in MetaMask.

2. Add Questions (Teacher)

1. Access the Deployed Contract:

   • Once deployed, locate the contract's interface under the "Deployed Contracts" section.

2. Add a Question:

   • Use the addQuestion function to add a new question.
   • Input the question text and correct answer, then click "transact".

   Example:

   • questionText: "What is the time complexity of binary search?"
   • correctAnswer: "O(log n)"

3. Submit Answers (Students)

1. Submit Answers:

   • Students can submit their answers using the submitAnswers function.
   • Provide an array of answers corresponding to the questions, then click "transact".

   Example:

   • If there are 3 questions, submit the answers as: ["O(log n)", "Linked List", "3.5"].

2. View Score:

   • Students can view their score by calling the getScore function.

4. View All Questions

1. Get All Questions:
   • Students can view all the stored questions by calling the getAllQuestions function.
   • This returns an array of all the question texts.

Example Usage

• The teacher deploys the contract and adds several questions.
• Students interact with the contract to view the questions, submit their answers, and view their scores.

Contract Address

Network: EDUCHAIN

• Contract Address: 0x2c53DAA191365e3BD007Bb70627232A43e9dB4c1

Vision

The vision for this project is to create a decentralized and transparent exam system where exam questions and grading are managed on the blockchain, ensuring integrity and accessibility.

Future Scope

• Enhanced Features: Integration of more advanced features like multiple-choice questions, timed exams, or automatic feedback.
• Scalability: Explore deployment on other Ethereum-compatible networks for broader accessibility.
• User Interface: Develop a user-friendly front-end application for easier interaction with the smart contract.

Contact Details

• Developer: Shahin Sha Alomgir
• Email: Shahinxsha@gmail.com
• GitHub: https://github.com/Nukeio

Security Considerations

• Teacher Privileges: Only the teacher (contract deployer) can add questions.
• Answer Submission: Students can only submit their answers once, and all questions must be answered.

Conclusion

This Solidity smart contract provides a basic framework for an exam system on the blockchain. It is a simple yet effective way to demonstrate how decentralized exams can be implemented using smart contracts.

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