Computer Science.

Build fluency with binary and hexadecimal registers through generated IGCSE and AS questions.

Paint a bitmap, change its colour depth, and compare normal, RLE and Huffman encoding.

Change sample rate and resolution, then compare the reconstructed signal visually and by listening.

Type text and see the code stored for each character, then compare restricted ASCII with Unicode and UTF-8 to find which characters can be stored and how many bytes each one takes.

Change bits in a message on its way, choose odd or even parity and row or block checks, then send and see what the receiver catches and how ACKs and resends get the original through.

Wire two devices with one or two cables, bend, move and add return wires, then send a byte and see what arrives: lost bits, late bits, interference and the checks that catch it.

Cut a message into packets, connect routers and send it: watch packets take their own routes and arrive out of order, then see B rebuild the message and check it with a checksum.

Send a message along a line someone is watching, put real keys in the locks, choose how a key reaches the receiver and see who can read the message at each end and at the tap.

Type a web address and press Go, then follow the browser asking DNS for the IP address, the request to that server and the HTML that comes back, and change the address to see which parts change.

Step a real program through the CPU one tick at a time, follow each instruction to the decoder, then edit RAM values and immediate numbers to see where an operand comes from and what is stored.

Build the software layers, power on the system and test whether an application can run.

Run programs that need pages from the drive, decide which page leaves full RAM, then add a page file and a cache shelf and compare how long the CPU waits for each read.

Wire a sensor, the CPU and an actuator on a bottle line, then edit the control flowchart and run real bottles to see whether each one is weighed and pushed into the right lane.

Build gate circuits for two keys, a heat-triggered fan with a Stop switch and a card-entry door, test every switch combination and compare the output with the truth table each one needs.

Build and test Python programs through guided examples and challenges covering input, selection, iteration, lists and functions.

Write, synchronize, run and trace Cambridge-style pseudocode alongside Python.