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Start here1What an Operating System Does2Windows, UNIX, and Linux3Phones and Tablets4Updates and End of SupportPractice and quizWords and resources

Start hereWelcome

Listen to the story1:09

Think about the tribal administration building on a busy Monday. Programs need the meeting room, staff need records from the filing cabinets, and visitors come and go through the front door. One person keeps it all running: the building manager. The manager books the meeting room so groups take turns, knows which drawer holds each record, and keeps the keys. Nobody walks into a locked office without the manager saying yes. Your computer and phone have a manager like this too. It is called the operating system, and this class shows you what it does, where it came from, and how to keep it up to date.

What you will learn

  • Explain what an operating system (OS) does for your apps, your files, and your safety
  • Tell how Windows, UNIX, and Linux differ, and how macOS, ChromeOS, Android, iOS, and iPadOS fit in the family tree
  • Find which operating system and version your phone and computer run
  • Turn on automatic updates and know what it means when support for a system ends

In this class

1What an Operating System DoesThe operating system is the building manager between you, your apps, and the hardware.1 picture2Windows, UNIX, and LinuxWhere each one came from, who makes it, where you meet it, and how they differ.2 pictures3Phones and TabletsAndroid and iOS run almost every phone, and both grew from the same families.1 picture4Updates and End of SupportWhy updates matter, and what to do when a system stops getting them.1 picture✓Practice and quizTry it yourself, the three things to remember, and a short quiz.

Part 1What an Operating System Does

The operating system is the building manager between you, your apps, and the hardware.

The Operating System Is the Building Manager
Listen to this part2:00
The Operating System Is the Building ManagerOn the left, four layers stacked from top to bottom: you, apps, the operating system, and hardware. On the right, a cut-away tribal office building: apps wait at the front desk, where a manager sends work up to the meeting room (the CPU) and the filing cabinets (storage), and keeps the keys beside the front door that leads to the network.THE OPERATING SYSTEM IS THE BUILDING MANAGERThe layersYouAppsOperating systemHardwareMeeting room = CPUIn use: Photos appFiling cabinets = storageEmailBrowserGameFRONT DESKKeysFront doorApps askThe OS decidesDoor = network123456
Read all 6 details
  1. 1Layers: you, apps, the OS, hardware. Think of your device in layers. You use apps. Apps ask the operating system (OS) for what they need. The OS works the hardware, the parts inside the box. The OS sits in the middle, so apps do not have to know every part.
  2. 2The manager. The National Institute of Standards and Technology (NIST) calls an OS the software that manages the hardware and gives programs common services. It is the first program to load when you turn the device on, and it runs everything after that, like a building manager.
  3. 3Apps ask first. An app, also called a program, cannot grab the processor, files, or internet on its own. It asks the operating system, like a visitor checking in at the front desk. The OS takes turns so every app gets what it needs.
  4. 4Meeting room: the processor. The CPU (Central Processing Unit) is the meeting room where work gets done. The OS books it in tiny time slots, switching between apps so fast that they all seem to run at once.
  5. 5Filing cabinets: storage and files. The OS keeps track of every file and folder in storage, like a building manager who knows which drawer holds each record. When you save a photo, the OS picks where it goes and remembers it.
  6. 6Keys and the front door. The OS keeps the keys. It checks your password or fingerprint, gives each person in the house their own account, and decides which apps may go out the front door to the internet, the network.

The manager's five jobs

Runs the hardware

Turns on the parts inside and gives each app a turn on the CPU (Central Processing Unit) and memory.

Runs your apps

Starts, stops, and switches between the apps you open.

Keeps your files

Knows where every photo, document, and folder is stored.

Guards the door

Checks passwords, keeps each person's account separate, and controls who reaches the network.

Gets updates

Brings in fixes from the maker to close security holes and repair problems.

← Start here

Part 2Windows, UNIX, and Linux

Where each one came from, who makes it, where you meet it, and how they differ.

The Operating System Family Tree
Listen to this part1:54
The Operating System Family TreeThree trees stand in a sagebrush valley. The UNIX tree from Bell Labs, 1969, has branches for macOS, iOS, and iPadOS. A seed of UNIX ideas grows a second tree, Linux from 1991, with branches for Android, many web servers, and ChromeOS. A separate Windows tree from 1985 has a green Windows 11 branch and a bare Windows 10 branch whose support has ended.THE OPERATING SYSTEM FAMILY TREEmacOSMac computersiOSiPadOSUNIXBell Labs, 1969AndroidMany webserversChromeOSLinuxHelsinki, 1991UNIX ideasWindows 11Windows 10support endedWindowsMicrosoft, 1985A separate family12345
Read all 5 details
  1. 1UNIX: the old root. UNIX was written in 1969 at AT&T Bell Labs by Kenneth Thompson and Dennis Ritchie, on a spare minicomputer. Many of today's systems grew from it or borrowed its ideas.
  2. 2Apple's branch. Apple's macOS, the system on Mac computers, is certified as UNIX by The Open Group. Apple also makes iOS for the iPhone. In 2019 Apple announced iPadOS for the iPad, built on the same foundation as iOS.
  3. 3Linux: a new tree from UNIX ideas. In 1991, a student in Finland named Linus Torvalds began writing a free operating system, Linux. The Linux part is the kernel, the core that talks to the hardware. A distribution wraps the kernel with apps and tools into a complete Linux system.
  4. 4Linux branches out. Android phones run on a kernel based on Linux. Many web servers that send you websites run Linux too. Google also makes ChromeOS for Chromebooks, and in 2026 announced Googlebook OS, which brings together ChromeOS and Android technology.
  5. 5Windows: its own family. Microsoft announced Windows in 1983, and Windows 1.0 came out in 1985. It is a separate family, not built from UNIX. Windows 11 came out in 2021. Windows 10 support ended on October 14, 2025, so that branch no longer grows.
Four Computer Families, Side by Side
Listen to this picture1:36
Four Computer Families, Side by SideFour laptops with different screens, labeled Windows, macOS, Linux, and ChromeOS. Under each, a card says who makes it, where you see it, and how it updates. A bar at the bottom shows worldwide desktop share for September 2026: Windows 76.4%, Mac 16.8%, Linux 4.5%, ChromeOS 2.3%.FOUR COMPUTER FAMILIES, SIDE BY SIDEWindowsMade byMicrosoftWhere you see itMost home, school,and office PCsHow it updatesWindows Update,in SettingsmacOSMade byAppleWhere you see itOnly on Apple'sMac computersHow it updatesSoftware Update, inSystem SettingsLinuxMade byMany groups; freeWhere you see itWeb servers andsome home PCsHow it updatesThe update tool ofyour distributionChromeOSMade byGoogleWhere you see itChromebooks, oftenin schoolsHow it updatesAutomatic, fromGoogleDesktop share worldwide, September 2026 (StatCounter)Windows 76.4%Mac 16.8%Linux 4.5%ChromeOS 2.3%12345
Read all 5 details
  1. 1Windows. Microsoft makes Windows. You find it on most home, school, and office PCs (personal computers), made by many different brands. The cost of Windows is usually part of the price of the computer. Updates come through Windows Update in Settings.
  2. 2macOS. Apple makes macOS, and it comes on Apple's Mac computers. Apple makes both the computer and the operating system. Updates come through Software Update in System Settings.
  3. 3Linux. Linux is free to download and use. Many groups, from volunteers to companies, put together their own distributions, which are complete Linux systems. It runs many web servers and some home and office computers.
  4. 4ChromeOS. Google makes ChromeOS for Chromebooks, laptops made by many brands and common in schools. Most of the work happens in the web browser. Google says today's Chromebooks will keep getting updates through mid-2034.
  5. 5Who uses what. StatCounter's worldwide numbers for September 2026 give Windows about 76% of desktop and laptop use. Apple Mac computers have about 17% (StatCounter lists them under two names, OS X and macOS), Linux about 4.5%, and ChromeOS about 2.3%.

Windows, UNIX, and Linux at a glance

WindowsUNIX (and macOS)Linux
StartedAnnounced 1983, first released 19851969, at AT&T Bell Labs1991, by Linus Torvalds in Finland
Who makes itMicrosoftUNIX began at Bell Labs; today Apple's macOS is a certified UNIXVolunteers and companies; many groups make their own distributions
Cost in generalUsually part of the price of a new PC (personal computer)macOS comes with Apple's Mac computersFree to download and use
Where you meet itMost home, school, and office PCsMac computersMany web servers, Android phones (its kernel), and some PCs
← What an Operating System Does

Part 3Phones and Tablets

Android and iOS run almost every phone, and both grew from the same families.

Phones and Tablets: Android and iOS
Listen to this part1:43
Phones and Tablets: Android and iOSOn the left, three Android phones from different makers. In the middle, an iPhone running iOS and an iPad running iPadOS. On the right, a grid of 100 squares shows worldwide phone share from StatCounter for September 2026: 69 green squares for Android and 31 blue for iOS. A card at the bottom shows where to find software updates on each kind of phone.PHONES AND TABLETS: ANDROID AND IOSAndroidGoogle, on phones from many brandsDifferent makers, one systemiOS and iPadOSApple, only on its own devicesiPhone: iOSiPad: iPadOSPhone share, Sept. 2026Android 69%iOS 31%Where to find updates on your phoneAndroid: Settings, then Software update(often under System; names vary by maker)iPhone and iPad: Settings, thenGeneral, then Software Update12345
Read all 5 details
  1. 1Android. Google makes Android, and many brands sell phones and tablets that run it. Android is built on a kernel based on Linux. Because each brand adds its own touches, menus can look a little different from phone to phone.
  2. 2iOS on iPhone. Apple makes iOS, and it runs only on Apple's iPhone. Apple makes both the phone and the operating system, so updates come straight from Apple.
  3. 3iPadOS on iPad. In 2019 Apple announced iPadOS for the iPad. Apple says it is built on the same foundation as iOS, with extra features for the bigger screen. If you know an iPhone, an iPad will feel familiar.
  4. 4About 7 in 10 phones are Android. StatCounter's worldwide numbers for September 2026 show Android at 69.17% of mobile use and iOS at 30.81%. In the picture, each small square stands for 1%: about 69 squares for Android and 31 for iOS.
  5. 5Find your updates. On an Android phone, open Settings and look for Software update, often under System. On an iPhone or iPad, open Settings, then General, then Software Update. Turn on automatic updates while you are there.
← Windows, UNIX, and Linux

Part 4Updates and End of Support

Why updates matter, and what to do when a system stops getting them.

Updates and End of Support
Listen to this part1:39
Updates and End of SupportTwo office buildings in a valley. On the left, a supported building with lit windows, where the manager on a ladder adds a new lock, under a card showing automatic updates turned on. On the right, a dim building with a cracked window and an open red lock, with a calendar showing October 14, 2025, when Windows 10 support ended. A yellow sign between them says Plan your move.UPDATES AND END OF SUPPORTAutomatic updatesONStill supportedPlan your moveSupport endedOCT142025Fixes keep comingNo more fixes12345
Read all 5 details
  1. 1What an update does. An update is the maker sending a fix. Most updates close security holes that thieves could use, fix problems, or add new features. It is like the building manager putting a stronger lock on a window.
  2. 2Turn on automatic updates. The Cybersecurity and Infrastructure Security Agency (CISA) says to turn on automatic updates. Then fixes arrive on their own, often overnight. Keep the device plugged in and restart it when it asks.
  3. 3End of support. Every operating system version has an end date. Microsoft ended support for Windows 10 on October 14, 2025. After that date, the maker stops sending fixes, even though the computer still turns on.
  4. 4Why it matters. Without updates, new security holes stay open, like a broken window nobody comes to fix. The longer a system goes without fixes, the more open holes it has.
  5. 5Plan your move. Check what version you run and when its support ends. The newest Windows is Windows 11, version 26H2, released on September 29, 2026. Google says today's Chromebooks get updates through mid-2034. Plan an upgrade or a new device before your date arrives.

Still on Windows 10?

Microsoft ended support for Windows 10 on October 14, 2025. The computer still turns on, but Microsoft no longer sends it fixes. Check Settings, then System, then About. If it says Windows 10, ask a trusted helper about moving to Windows 11 or to a newer device, and move your important files and passwords first.

← Phones and Tablets

ReviewPractice and quiz

Listen to the practice steps1:41

Try it at home

Fifteen minutes with your own phone and computer. Menu names differ a little from device to device.

  1. Find your phone's system. iPhone: Settings, then General, then About, and look for iOS Version. Android: Settings, then About phone, and look for Android version (sometimes under Software information).
  2. Find your computer's system. Windows: Settings, then System, then About, and look under Windows specifications for Edition and Version. Mac: the Apple menu, then About This Mac. Chromebook: Settings, then About ChromeOS.
  3. Write down each name and version number. If your computer says Windows 10, its support ended on October 14, 2025, so make a plan to move.
  4. Turn on automatic updates. iPhone or iPad: Settings, then General, then Software Update, then Automatic Updates. Android: Settings, then Software update (often under System). Windows: Settings, then Windows Update. Mac: System Settings, then General, then Software Update.
  5. Install any update that is waiting. Plug the device in first, and let it restart when it asks.
  6. Open your app store and update your apps too. They get security fixes just like the operating system.

Remember

The OS is the manager between apps and hardware

UNIX, Linux, and Windows are different families

Turn on automatic updates; know your end date

Check what you learned

1. Your granddaughter has a game, a web browser, and a photo app open on the family laptop. What decides which app gets to use the processor next?

2. Your aunt's laptop runs Windows 10. It still turns on and works fine. What is the real risk?

3. The youth center is buying phones from three different brands, none of them Apple. Which operating system will those phones most likely run?

4. You are typing a letter when your computer says an update is ready. What is the best choice?

5. Your cousin wants a free operating system she can download for a computer she built herself. Which one fits?

← Updates and End of Support

ResourcesWords and resources

Words to know

Operating system (OS)
Operating system. The main software that manages a device's hardware, runs apps, keeps files, and guards security. It is the first program to load when you turn the device on.
App
Short for application. A program that does one job for you, like email, photos, or a web browser. Apps ask the operating system for what they need.
Hardware
The physical parts of a device you could touch, like the processor, memory, storage, screen, and radios.
Kernel
The core of an operating system. It talks directly to the hardware and decides which app gets the processor and memory.
UNIX
An operating system written in 1969 at AT&T Bell Labs. Many later systems grew from it or borrowed its ideas, and Apple's macOS is a certified UNIX.
Linux
A free operating system kernel started by Linus Torvalds in 1991. It runs many web servers, and Android's kernel is based on it.
Distribution
A complete Linux system: the Linux kernel plus the apps, tools, and settings that make it ready to use.
Windows
Microsoft's operating system for personal computers, first released in 1985. The current version is Windows 11.
macOS
Apple's operating system for Mac computers. It is certified as UNIX.
ChromeOS
Google's operating system for Chromebook laptops, where most work happens in the web browser.
Android
Google's operating system for phones and tablets, sold by many brands. Its kernel is based on Linux.
iOS
Apple's operating system for the iPhone.
iPadOS
Apple's operating system for the iPad, announced in 2019 and built on the same foundation as iOS.
Software update
A fix or improvement sent by the maker. Most updates close security holes, repair problems, or add features.
End of support
The date a maker stops sending updates for a version of its software. The device still works, but no new fixes arrive.
CISA
Cybersecurity and Infrastructure Security Agency. The United States government agency that helps people and organizations stay safe online.

Learn more

For teachers and digital navigators: how to run this class (45 minutes)

Lesson plan

  1. 5 minOpen with the building manager story. Ask: who keeps our administration building running, and what would happen without them?
  2. 10 minPart 1: act it out. One volunteer is the manager with the keys. Three volunteers are apps holding signs (Email, Browser, Game) who must ask the manager before using the meeting room, the files, or the front door.
  3. 10 minPart 2: walk through the family tree and the side-by-side picture. Ask people which systems they have seen at home, school, work, or the clinic.
  4. 5 minPart 3: the phone picture. Have everyone hold up their phone: who has Android and who has an iPhone?
  5. 10 minPart 4 and Try it at home: everyone finds their system and version and turns on automatic updates. Pair people up so they can help each other.
  6. 5 minQuiz together with a show of hands, then the three Remember cards.

What you need

  • Projector or large TV for the slides
  • Printed handouts, one per person
  • Props for the building manager game: a ring of keys, a few folders, and paper signs that say Meeting room, Filing cabinet, and Front door
  • Participants' own phones, tablets, or laptops, charged
  • Optional: one Windows laptop, one Chromebook, and one Mac or iPad to pass around

Talk about it

  • Which operating systems do you use in a normal week, at home, at work, at school, or at the clinic?
  • Has an update ever surprised you or got in your way? How could you plan for updates instead?
  • Who in our community might still be using an old computer that no longer gets updates, and how could we help them?

The PowerPoint slides follow this plan, with the story and every picture detail in the speaker notes.

References

  1. Android Open Source Project. (n.d.). Kernel overview. https://source.android.com/docs/core/architecture/kernel
  2. Apple. (2019, June 3). The new iPadOS powers unique experiences designed for iPad [Press release]. https://www.apple.com/newsroom/2019/06/the-new-ipados-powers-unique-experiences-designed-for-ipad/
  3. Brock, D. C. (2019, October 17). The earliest Unix code: An anniversary source code release. Computer History Museum. https://computerhistory.org/blog/the-earliest-unix-code-an-anniversary-source-code-release/
  4. Computer History Museum. (n.d.-a). 1969 timeline of computer history. https://www.computerhistory.org/timeline/1969/
  5. Computer History Museum. (n.d.-b). What happened on November 10th. This Day in History. https://www.computerhistory.org/tdih/November/10/
  6. Cybersecurity and Infrastructure Security Agency. (n.d.). Update software. https://www.cisa.gov/secure-our-world/update-software
  7. Google. (2026). Googlebook OS and ChromeOS updates. Google Chrome Enterprise Help. https://support.google.com/chrome/a/answer/16634428?hl=en
  8. Microsoft. (2025). Windows 10 support has ended on October 14, 2025. Microsoft Support. https://support.microsoft.com/en-us/windows/deployment/updates-lifecycle/windows-10-support-has-ended-on-october-14-2025
  9. Microsoft. (2026). Windows 11 release information. Microsoft Learn. https://learn.microsoft.com/en-us/windows/release-health/windows11-release-information
  10. National Institute of Standards and Technology. (n.d.). Operating system. CSRC Glossary. https://csrc.nist.gov/glossary/term/operating_system
  11. Perlow, J. (2020, March 2). The Linux Foundation: It's not just the Linux operating system. Linux Foundation. https://www.linuxfoundation.org/blog/blog/the-linux-foundation-its-not-just-the-linux-operating-system
  12. StatCounter. (2026a). Desktop operating system market share worldwide. https://gs.statcounter.com/os-market-share/desktop/worldwide
  13. StatCounter. (2026b). Mobile operating system market share worldwide. https://gs.statcounter.com/os-market-share/mobile/worldwide
  14. The Linux Kernel Organization. (n.d.). About Linux kernel. The Linux Kernel Archives. https://www.kernel.org/linux.html
  15. The Open Group. (2025). Open Brand register: macOS version 26.0 Tahoe. https://www.opengroup.org/openbrand/register/brand3725.htm
← Practice and quiz

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