Session 3 — Exercises: Fork, Pull Request, and Issues

Last updated on 2026-03-03 | Edit this page

Overview

In this session you will learn to contribute to a repository you do not own by forking it, and you will practise using GitHub Issues.

Time frame: approximately 75 minutes of hands-on work.

Pair setup: work in the same pairs as Session 2. This time you will contribute to your partner’s repository without being a collaborator.

Task 1: Fork Workflow

Level 1 — Fork your partner’s repository

  1. Go to your partner’s repository on GitHub (the one from previous sessions).
  2. Click the Fork button in the top-right corner.
  3. Keep the default settings and click Create fork.
  4. Clone your fork (not the original) in GitHub Desktop.
Callout

Checkpoint 1

You now have a copy of your partner’s repository under your own GitHub account. GitHub Desktop shows the fork as your current repository.

Level 2 — Make changes on your fork

  1. Create a new branch on your fork (e.g. improve-readme).
  2. Edit README.md — for example, fix a typo, add a section, or improve formatting.
  3. Commit with a clear message (e.g. Improve README formatting).
  4. Push the branch to your fork.

Level 3 — Add a new file

In addition to editing the README, create a new file (e.g. tips.md) with helpful tips or notes. Commit and push this as a separate commit on the same branch.

Task 2: Pull Request to Upstream

Level 1 — Open a PR against the original repository

  1. On GitHub, navigate to your fork.
  2. Click Contribute → Open pull request.
  3. Make sure the base repository is your partner’s repo and the base branch is main.
  4. Fill in a descriptive title and description explaining your changes.
  5. Click Create pull request.
Callout

Checkpoint 2

Your partner can see the pull request on their repository. The PR shows your changes and allows them to review and comment.

Partner's repo (upstream)     Your fork (origin)       Your computer (local)
         │                          │                          │
         │       fork               │                          │
         │◄─────────────────────────│                          │
         │                          │        clone             │
         │                          │◄─────────────────────────│
         │                          │                          │
         │                          │   edit + commit + push   │
         │                          │◄─────────────────────────│
         │     pull request         │                          │
         │◄─────────────────────────│                          │

Level 2 — Review your partner’s PR

  1. Go to your own repository (not your fork).
  2. Open the Pull requests tab — you should see your partner’s PR.
  3. Go to the Files changed tab and review the diff.
  4. Leave at least one comment on a specific line.
  5. If the changes look good, Approve the PR.

Level 3 — Merge or discuss

  1. If the PR is approved, click Merge pull request → Confirm merge.
  2. If changes are needed, request changes and have your partner update the PR by pushing additional commits to their branch.
  3. After merging, verify that the changes appear on main.

Task 3: GitHub Issues

Level 1 — Create an issue

  1. On your own repository, go to the Issues tab.
  2. Click New issue.
  3. Write a clear title (e.g. “Add a licence file”).
  4. In the description, explain what needs to be done and why.
  5. Submit the issue.
Callout

Checkpoint 3

Your issue is visible in the Issues tab with a unique number (e.g. #1).

Level 2 — Labels and linking

  1. Add a label to your issue (e.g. enhancement or documentation). If no labels exist yet, create one.
  2. Create a new branch, make the change described in the issue, and open a PR.
  3. In the PR description, write Closes #1 (replacing 1 with your issue number) to link the PR to the issue.

When you include Closes #1, Fixes #1, or Resolves #1 in a PR description, GitHub will automatically close the linked issue when the PR is merged.

Level 3 — Issue templates and advanced features

  1. Explore the Labels page and create a few custom labels for your repository (e.g. help wanted, good first issue).
  2. Write a second issue with a detailed bug report format:
    • Steps to reproduce
    • Expected behaviour
    • Actual behaviour
  3. Cross-reference the two issues by mentioning one in the other (e.g. “Related to #1”).

Summary

By the end of this session you should have: