Session 2 — Collaboration: Merge, Conflict, and PR

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

Session Plan

Duration: 90 minutes Goal: practise merging, resolve a conflict, create and merge a pull request.

Prerequisite material: Material 2 — Collaboration, Branching and Pull Requests.

1. Pair Setup (5 min)

  • Organise participants into pairs (Person A and Person B).
  • Person A shares their repository with Person B as a collaborator.
Callout

Before the exercises begin

Take 5 minutes to recap the key concepts from Material 2:

  • What is a merge? When does it work automatically?
  • What is a conflict? When does it happen?
  • What is a branch? What is a pull request?

Ask 2–3 participants to explain in their own words.

2. Scenario 1 — Mergeable Changes (20 min)

  • Both partners edit different parts of the same file simultaneously.
  • Person A pushes first; Person B pulls, then pushes.
  • Git merges automatically.
  • Debrief: why did this work without a conflict?

3. Scenario 2 — Conflict (30 min)

  • Both partners edit the same line of the same file.
  • Person A pushes first; Person B encounters a conflict when pulling.
  • Walk through the conflict resolution process:
    1. Identify the conflict markers in the file.
    2. Decide which version to keep (or combine both).
    3. Remove the markers, save, commit, push.
Callout

Milestone: first conflict resolved

After the first pair resolves their conflict, pause the room briefly. Ask them to explain what happened to the group. This reinforces learning and helps struggling pairs.

4. Branch and Pull Request in GitHub Desktop (25 min)

  • Demo: create a branch, make changes, publish the branch, open a PR.
  • Participants create their own branch and PR.
  • Partners review each other’s PRs on GitHub.
  • Merge the PR.
Callout

Important: PR review etiquette

Before participants start reviewing, briefly discuss:

  • Be constructive and specific in comments.
  • Use the Files changed tab to see exactly what was modified.
  • Approve only if you actually looked at the changes.

5. Best Practice Tips (10 min)

  • Pull before you start working (avoid unnecessary conflicts).
  • Communicate with your collaborators about who is working on what.
  • Use branches for any non-trivial change.
  • Keep pull requests small and focused.

Exercise File

See Session 2 — Exercises for the detailed student tasks.