GCSE Computer Science
Algorithms and programming
revision.
Computational thinking, core constructs, and the logic that sits under every IF and WHILE.
Algorithms and programming guides
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Students type: robust testing GCSE computer science
Open guide Revision guideDecomposition and abstractionStudents type: decomposition abstraction GCSE
Open guide Revision guideHigh-level and low-level languagesStudents type: high level vs low level GCSE
Open guide Revision guideSQL SELECT queriesStudents type: SQL SELECT FROM WHERE GCSE computer science
Open guide Revision guideSubroutines and functionsStudents type: functions vs procedures GCSE computer science
Open guide Revision guideArrays and listsStudents type: arrays GCSE computer science indexing 0
Open guide Revision guideSequence, selection and iterationStudents type: sequence selection iteration GCSE computer science
Open guide Revision guideMerge sortStudents type: merge sort GCSE computer science
Open guide Revision guideBubble sortStudents type: bubble sort GCSE computer science
Open guide Revision guideBinary searchStudents type: binary search GCSE computer science
Open guide Revision guideLinear searchStudents type: linear search GCSE computer science
Open guide Revision guideTrace tablesStudents type: trace table GCSE computer science
Open guideAlgorithms
Decomposition, abstraction, searching, sorting, and how to prove an algorithm works with a trace table.
Programming basics
Sequence, selection, iteration, data types, strings, arrays, functions, validation and the three faces of errors.
Boolean logic
AND, OR and NOT gates, truth tables, and how to read a logic circuit the way the paper draws it.
Trace tables
GCSE Computer Science trace tables: one column per variable, one line of the algorithm at a time, and the off-by-one errors that drop the last output mark.
Linear search
GCSE Computer Science linear search: check each item in order, works on unsorted lists, worst case n comparisons, and when it is the right algorithm to name.
Binary search
GCSE Computer Science binary search: the list must be sorted, each step halves the search space, and a full midpoint trace is how you prove it.
Bubble sort
GCSE Computer Science bubble sort: compare neighbouring pairs, swap if they are out of order, use a flag or a shrinking tail, and trace a four-item list.
Merge sort
GCSE Computer Science merge sort: split the list to one-item pieces, merge sorted halves back together, and compare time and extra memory with bubble sort.
Sequence, selection and iteration
GCSE Computer Science programming constructs: sequence, IF selection, WHILE and FOR iteration, and how nested decisions and loops are read in exam algorithms.
Arrays and lists
GCSE Computer Science arrays and lists: indexing from 0 or 1, bounds, iteration through items, and the out-of-range errors that crash a dry-run.
Subroutines and functions
GCSE Computer Science subroutines and functions: parameters, return values, local versus global variables, and why reuse beats copy-paste in exam code.
SQL SELECT queries
GCSE Computer Science SQL: SELECT, FROM and WHERE, the difference between = and LIKE, and how to write a query that actually matches the table in the paper.
High-level and low-level languages
GCSE Computer Science high-level versus low-level languages: abstraction, portability, assembly, machine code, and when each level is chosen.
Decomposition and abstraction
GCSE Computer Science decomposition and abstraction: break problems into sub-problems, hide detail behind interfaces, and design algorithms at the right level.
Robust testing
GCSE Computer Science robust testing: normal, boundary and erroneous data, test plans, expected versus actual, and why testing cannot prove zero bugs.
Keep going
More GCSE Computer Science
in the same style.
GCSE Computer Science revision for algorithms, programming, binary, networks, cyber security, systems architecture and Boolean logic — with trace tables, not hand-waving.
All Computer Science revision