---
title: "The DOM: your page as a live tree"
course: "BE101 · What runs behind a website"
unit: "Making pages interactive with JS"
lesson: 21 of 39
source: https://open.maestrocollege.edu/what-runs-behind-a-website/the-dom-your-page-as-a-live-tree
publisher: Maestro College
---

# The DOM: your page as a live tree

Lesson 21 of 39 in **What runs behind a website** (BE101), unit "Making pages interactive with JS". An open lesson from Maestro College.

## What the learner will be able to do
- Identify the DOM as a live tree of objects that the browser builds from HTML at runtime.
- Distinguish between the static HTML source file and the live DOM that the browser can update without changing the source file.
- Use the Elements panel in DevTools to explore the DOM tree and find specific elements.

## Teaching notes
No JavaScript in this lesson.

## Course teaching approach
- Start from a real-world problem, then introduce the concept as the solution.
- Keep it true beginner level, hands-on, a little gamified. The learner should feel they are winning.
- Balance explanation, demonstration and practice. No copy-paste exercises: give small story-based tasks.
- End with one fun closed question about the topic.

## How to use this document
You are acting as a tutor for a learner on Maestro Open. Teach from this document, one small step at a time. Ask the learner to try things, wait for their answer, then give feedback. Keep it beginner-friendly. If the lesson involves code or spreadsheets and you cannot run them, ask the learner to try it on their own computer and paste the result back. Do not award grades, credit or certificates.

## When the lesson is done
The lesson is complete only when the learner has shown they can do every outcome listed above. Check each one with a small task or question; if an answer is wrong, explain and let them try again before moving on.
When every outcome is covered:
1. Say clearly: "Lesson 21 complete: The DOM: your page as a live tree."
2. Give a two-line recap of what they learned.
3. Name the next lesson, "Selecting elements" (lesson 22 of 39), and give the learner its link: https://open.maestrocollege.edu/what-runs-behind-a-website/selecting-elements.md. Tell them to paste that page into this chat, or fetch it yourself if you can open links, then start it the same way. Do not start teaching the next lesson's topic until the learner has it.

Previous lesson: JavaScript in the browser
Next lesson: Selecting elements