How the Internet Works

Lesson overview

What actually happens between tapping a link and the page appearing — across a planet-sized network with no one in charge. This module climbs from an everyday intuition to the real mechanism, then names the Stanford course it descends from.

Teacher script · ~45 min

1. 0–5

   Hook

   The internet isn't a cloud or a place — it's millions of computers agreeing to pass messages for each other, like passing a note across a huge classroom hand to hand. No single computer is in charge. Your message gets chopped into small pieces, each finds its own way across, and they're reassembled at the other end.

2. 5–15

   Explore

   Students do the activity in pairs: Think of DNS as contacts on a phone: you tap 'Mom,' the phone dials the number. Names for humans, numbers for the network.

3. 15–30

   Explain

   Computers made by different companies cooperate only because they follow shared PROTOCOLS — agreed rules for how to talk (IP moves packets, TCP makes sure none are lost, HTTP carries web pages). The 's' in HTTPS adds ENCRYPTION: it scrambles your message so only the intended site can read it. That lock icon is why a password you send can't be read by the computers relaying it.

4. 30–40

   Connect to the summit

   Show students this is the real thing professionals build: The real networking picture. What actually happens between tapping a link and the page appearing — across a planet-sized network with no one in charge.

5. 40–45

   Check

   Run the formative check below. Anyone who can explain a key term in their own words has it.

Student activity

Slides

Formative check

• 1.In your own words, what is "Packet"? (Looking for: A small piece your message is chopped into, each routed across the network on its own.)
• 2.In your own words, what is "IP address"? (Looking for: A computer's number on the network, like a house address for messages.)
• 3.In your own words, what is "DNS"? (Looking for: The internet's phonebook: turns a human name into the numeric address behind it.)

Carry-away concepts

Packet

A small piece your message is chopped into, each routed across the network on its own.

IP address

A computer's number on the network, like a house address for messages.

DNS

The internet's phonebook: turns a human name into the numeric address behind it.

Protocol

An agreed set of rules that lets different computers talk to each other.

Encryption (HTTPS)

Scrambling a message so only the intended recipient can read it.

From the summit · the Stanford source