Beep! Tap the happy computer!
Hardware heroes

Where does thinking happen — and where do files sleep?

# CPU, memory and storage Three friends work together: ## CPU — the brain The **CPU** (Central Processing Unit) follows instructions very fast. Speed is often measured in GHz. ## RAM — the desk **RAM** is working memory. Open apps sit on this “desk”. When you switch the computer off, RAM usually forgets (it is volatile). ## Storage — the cupboard An **HDD** or **SSD** keeps files even after power off (non-volatile). SSD is usually faster and quieter. ## Easy picture - CPU = chef - RAM = kitchen counter - Storage = fridge / pantry A tiny desk (little RAM) makes the chef keep running to the fridge — the computer feels slow. > Tip: save your project often. RAM can lose work if power cuts; storage keeps the file. ## Three friends, one kitchen | Friend | Job | Forgets at power-off? | | --- | --- | --- | | CPU | Follows instructions | N/A — it is the cook, not a shelf | | RAM | Holds *open* work | Yes (volatile) | | SSD/HDD | Holds *saved* files | No (non-volatile) | ### GHz and GB — do not mix the units - **GHz** — how fast the CPU ticks (billions of cycles per second) - **GB of RAM** — how wide the desk is - **GB of SSD** — how big the cupboard is A 3 GHz CPU with 4 GB RAM can still feel slower than a 2 GHz CPU with 16 GB RAM if you open many apps. Desk size matters. ### HDD vs SSD HDD has spinning disks (like a tiny record player). SSD has no moving parts. SSD usually wins on speed and toughness in a school bag.

By the end of this lesson

Explain CPU vs RAM vs storage with the chef / counter / pantry picture, and say why we click Save.

Remember

  • CPU = brain / chef. It follows instructions. Speed often in GHz.
  • RAM = desk / kitchen counter. Open apps live here. Volatile — forgets when power dies.
  • Storage (HDD/SSD) = cupboard / pantry. Keeps files after shutdown. Non-volatile.
  • SSD is usually faster and quieter than HDD.
  • Save often: you copy from the RAM desk into the cupboard.

Worked examples

Cover the answer. Try the steps on paper, then open them.

Example 1 — Why a slow laptop feels slow

Only 4 GB RAM, 20 browser tabs.

  1. Each tab sits on the RAM desk.
  2. Desk overflows, so the chef keeps running to the pantry (storage).
  3. That running is called swapping — it feels laggy.

Answer: not enough RAM for the open work

Check: Closing tabs is like clearing the counter.

Example 2 — Power cut

You typed two pages and never saved. Power dies.

  1. The two pages lived in RAM.
  2. RAM forgets at power-off.
  3. Storage never received a file.
  4. Work is gone.

Answer: lost, because it was only in RAM

Check: Ctrl+S copies to storage.

Example 3 — Label the three

Chef, counter, pantry — match CPU, RAM, SSD.

  1. Chef = CPU
  2. Counter = RAM
  3. Pantry = SSD/HDD

Answer: CPU ; RAM ; storage

Check: Tiny counter + huge pantry still feels slow while cooking.

Common mistakes

Slip Calling RAM “permanent memory”.

Fix RAM is volatile working memory.

Permanent (until delete) is storage.

Slip Thinking a bigger monitor makes a faster CPU.

Fix Screen size is output, not thinking speed.

CPU and RAM decide snappiness.

Slip Never saving because “it is on the screen”.

Fix The screen is output of RAM. Storage needs Save.

Power cuts do not care about your screen.

Try on paper first

Write the answer, then tap Reveal. These are not the quiz — they are warm-ups.

1. Which forgets when power is off?

Answer: RAM

2. Which keeps a homework file overnight?

Answer: Storage (SSD/HDD)

3. The brain of the computer is the…

Answer: CPU

4. Why Save?

Answer: Copy work from RAM to storage

Touch practice

9 tap / type

Tap or type. Use the hint if you need it. Retry any miss — the why is the lesson.

Optional picture lab

After practice

Real world

Desk vs cupboard.

Connect

RAM vs disk in programming.

⭐ Star quiz

9 questions

Do the worked examples and touch practice first. Then take the quiz without peeking.

← Input and output All topics →