In Session 1 you met the outside of a computer: the monitor, keyboard, mouse and system unit. Today we open the box (in our imagination and in the 3D lab, never with a screwdriver!) and meet the three parts that do the real work. By the end you will know why some computers are fast, why some are slow, and why a power cut can eat your work.
Picture the kitchen behind a busy chop bar. Orders keep coming in: "One fufu and light soup! Two waakye!" Three things make the kitchen work:
| Part | What it does | You might see it written as⦠|
|---|---|---|
| Processor (CPU) | The "brain" that follows instructions and does every calculation, billions per second. | Intel Core i5, AMD Ryzen 5, Intel Celeron |
| Memory (RAM) | Holds the programmes and files you are using right now. | 4 GB, 8 GB or 16 GB RAM |
| Storage | Keeps your files, photos and programmes, even when the power is off. | 256 GB SSD, 1 TB hard drive |
People often mix these two up, because both are measured in GB. They are very different jobs.
• Very fast, but small (usually 4 to 16 GB).
• Holds only what you are working on now: open programmes, open files, open browser tabs.
• Temporary: it is wiped clean when the computer shuts down or the power goes off.
• Much bigger (often 256 GB to 1 TB or more), but slower to reach.
• Keeps everything: Windows, your programmes, saved documents, photos, music.
• Permanent: files stay there when the power is off, until you delete them.
a) Esi typed for 20 minutes and never saved. Kofi saved every 5 minutes. The power went off. Who lost more work, and why?
b) Yaw's laptop has 4 GB of RAM and a 1 TB drive. His friend says "1 TB is huge, so your laptop must be very fast!" Is the friend right? Explain using the kitchen.
Deep down, a computer stores everything as tiny on/off switches. Each one is a bit (it is either 0 or 1). Eight bits make one byte, which is enough to store one letter, such as A. From there, each step up the ladder is about 1,000 times bigger (exactly 1,024 inside the computer, but 1,000 is close enough for us).
| Thing | About how big? (sizes vary) |
|---|---|
| One SMS text message | Under 1 KB |
| A one-page typed letter (.docx) | About 20 to 50 KB |
| A photo taken on a phone | About 3 to 5 MB |
| A song (MP3) | About 4 MB |
| One hour of HD video | About 1 to 3 GB |
| Windows 11 itself | Tens of GB of storage |
Use 1 GB = 1,000 MB to keep the sums easy.
| Question | Answer |
|---|---|
| 1. How many 4 MB songs fit in 1 GB? | |
| 2. Naa's phone has 2 GB free. About how many 4 MB photos can she still take? | |
| 3. Which is bigger: 500 MB or 1 GB? | |
| 4. Put in order, smallest first: GB, KB, TB, MB |
| Storage | What it is | Speed | Cost per GB |
|---|---|---|---|
| Hard drive (HDD) | Spinning metal discs inside older and cheaper PCs. Big, but can break if knocked. | Slow | Cheap |
| SSD (solid-state drive) | Memory chips, no moving parts. Inside most new laptops. | Very fast | Medium |
| USB pen drive | Small and portable (Session 5). Easy to lose! | Medium | Medium |
| Memory card (microSD) | Tiny card for phones and cameras. | Medium | Medium |
| Phone storage | Built-in storage, for example "64 GB". | Fast | Costly |
| Cloud | Storage on someone else's computers, reached over the internet (Google Drive, OneDrive). | Needs internet | Free to start |
The letters after the dot in a file name are its extension. They tell Windows which programme opens the file.
.docx Word document
.xlsx Excel spreadsheet
.pptx PowerPoint slides
.pdf PDF (looks the same everywhere)
.jpg photo or picture
.mp4 video
.zip packed folder
Show extensions in File Explorer: Windows 11: View → Show → File name extensions. Windows 10: View tab → tick File name extensions. When you rename a file, never change or delete the extension, or the file may not open.
The club's study packs are ZIP files. To unpack one: right-click the .zip file → Extract Allβ¦ → Extract. A new normal folder appears next to it. Always extract first, then open the files from the new folder.
Open the Inside the Box 3D lab on your session page. Open the case, lift out the processor, memory and storage and read what each one does. Then run the chop bar kitchen with a small worktable and a big one, and write what changed:
Every computer can tell you what is inside it. You will be a detective and write a spec sheet (a list of the specifications, or main facts, about a machine).
| Spec sheet for my PC | What I found |
|---|---|
| Device name | |
| Processor (the cook) | |
| Installed RAM (the worktable) | |
| Windows edition | |
| Drive C: total size (the storeroom) | |
| Drive C: free space | |
| Class photos that fit (4 MB each) |
Compare with a neighbour: whose PC has the bigger worktable (RAM)? Whose storeroom has more free space?
| Problem | Best fix (choose one) |
|---|---|
| 1. Akosua has 25 browser tabs open, plus Word and a game. Everything is crawling. | |
| 2. In This PC, Kwame's C: drive bar is red: "1.2 GB free of 237 GB". The PC is slow and will not install updates. | |
| 3. The office PC is 10 years old, has an old hard drive and takes 5 minutes to start. |
Question 1: What is the difference between memory (RAM) and storage? Use the chop bar kitchen in your answer.
Question 2: Selasi's science project is saved only on one pen drive. What could go wrong, and what should he do?
Tick the column that reflects your confidence at the end of Session 6:
| Inside-the-Computer Competency | With Help | Almost Alone | All By Myself! |
|---|---|---|---|
| 1. I can explain what the processor, memory and storage do. | |||
| 2. I can put KB, MB, GB and TB in order and do simple size sums. | |||
| 3. I can find a PC's processor, RAM and free storage. | |||
| 4. I can show file extensions and extract a ZIP file. |
BIH JHS Tech Club Β· a Bozoma Innovation Hub programme Β· Your answers are saved only on this computer.