You spent part of Workshop 1 squinting at a circuit board and converting numbers to and from binary. The conversions might have felt like a maths puzzle disconnected from the hardware. This video closes that gap.

Carrie Anne Philbin walks you from "binary is just two states" all the way to how the same trick stores text, colours, photos, and music. By the end, the row of LEDs on your Raspberry Pi and the photo on your phone are using the *same* code — just at different scales.

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Crash Course Computer Science #4 — about 11 minutes. Carrie Anne moves quickly, so you might want to watch twice: once for the big picture, once with a notebook to follow the conversions.

- **Two states, one bit** — every binary digit is just "on" or "off". A switch, a wire with current or no current, a transistor open or closed. The hardware is genuinely that simple.

- **How 8 bits make a byte** — and why a byte can hold 256 different values (0 through 255). This is the same range you used in the booklet's binary scavenger hunt.

- **ASCII** — the agreement that 65 means `A`, 66 means `B`, and so on. Every keyboard, every text file, every chat message uses this (or its bigger cousin Unicode).

- **Colour as binary** — RGB is three bytes per pixel. Watch how Carrie Anne shows red = 255,0,0 and immediately you understand HTML colour codes for the rest of your life.

- **Why we say *kilobyte* / *megabyte* / *gigabyte*** — they're powers of two, not powers of ten. 1 KB ≈ 1024 bytes, not 1000.

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**<i class="fas fa-pencil-alt"></i> Your turn!** Grab a pen and have a crack at these.

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**<i class="fas fa-film"></i> Question** ① — A byte is 8 bits. Without looking it up, work out how many different values a byte can hold. (Hint: each bit doubles the count of possibilities.)

**<i class="fas fa-keyboard"></i> Question** ② — The letter `A` in ASCII is 65. The letter `B` is 66. What number is `Z`? What number is `a` (lowercase)?

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⚡ **Hint:** The capital letters are 26 in a row starting at 65. Lowercase letters start at 97.

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**<i class="fas fa-palette"></i> Question** ③ — A pixel of pure green in RGB is 0, 255, 0. What three numbers would you use for pure white? Pure black? Cyan (no red, full green, full blue)?

**<i class="fas fa-question-circle"></i> Question** ④ — In the video, Carrie Anne points out that everything on a computer — text, photos, sound, video — boils down to binary. Pick *one* thing on your phone (a photo, a song, a meme) and write a sentence about how it gets stored as 0s and 1s.

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