GCSE-readyGCSE and International GCSE Computer Science: common mistakes
The wrong answers students pick most often in our Computer Science questions, and why they are wrong. Read these before a test, then open the lesson for anything that surprises you.
Getting started
- What is an algorithm?
- Not “Rectangle”. A rectangle is a process.
- Not “Parallelogram”. A parallelogram is input or output.
- Not “Rounded rectangle”. A rounded rectangle is start or stop.
Topic 1: Computational thinking
- Decomposition and abstraction
- Not “Removing unnecessary detail”. That is abstraction.
- Variables, constants and operators
- Not “==”. == means equal to.
- Not “<>”. <> is not used in Python 3.
- Searching and sorting
- Not “It uses less memory”. Merge sort usually uses more memory, not less.
- Evaluating algorithms and test data
- Not “15”. 15 is normal data.
- Not “"sixteen"”. Text is erroneous data.
- Not “25”. 25 is erroneous: outside the range.
Topic 2: Data
- Hexadecimal
- Not “Computers store data in hex”. Computers always store data in binary. Hex is for humans.
Topic 4: Networks
- Networks, LANs, WANs and the internet
- Not “192.168.300.1”. 300 is above 255.
- Not “192.168.1.256”. 256 is above 255.
- Not “192.168.1”. Only three numbers.
Topic 6: Problem solving with programming
- Manipulating strings
- Not “answer.upper() == "yes"”. upper() gives "YES", which does not equal "yes".