Master the OCR A Level Computer Science (H446) exam with evidence-based tips. Learn how to maximize marks on high-tariff essays, avoid case-sensitivity pitfalls in LMC, and structure flawless OOP code.
A scientific or graphical calculator that meets JCQ regulations may be used (some GCSE Mathematics and Science papers are non-calculator). Graphical calculators must be set to exam mode; you must clear any stored programs, notes or data before the exam, and the calculator must not be able to retrieve stored text or formulae.
AO1: AO1: Demonstrate knowledge and understanding of the principles and concepts of computer science. (35%)
AO2: AO2: Apply knowledge and understanding of the principles and concepts of computer science to a given scenario, including the analysis of problems in computational terms. (40%)
AO3: AO3: Design, write and evaluate computer programs. Solve problems, evaluate systems and improve design. (25%)
根據歷屆試題與評分準則整理（2022–2024）。
計算機程式
Graph: zeros, intersections & turning points
Graphical calculator / GDC (exam mode)
用途: Plot a function to read its roots (zeros), points of intersection, and maxima/minima.
使用時機: Checking solutions, sketching, or solving where an analytic method is hard.
步驟
Graph the function(s) and use the built-in zero, intersect and maximum/minimum tools.
考試提示: Allowed under JCQ rules, but you must still show your method — an unsupported calculator answer earns no method marks. Clear all stored programs, notes and data (graphical calculators in exam mode) before the exam.
Numerical equation solver
Graphical calculator / GDC (exam mode)
用途: Solve an equation or find a variable numerically when an algebraic route is long or implicit.
使用時機: Iterative or implicit equations, or to confirm an algebraic solution.
步驟
Use the equation/zero solver, entering the equation and a sensible starting estimate.
考試提示: Allowed under JCQ rules, but you must still show your method — an unsupported calculator answer earns no method marks. Clear all stored programs, notes and data (graphical calculators in exam mode) before the exam.
Numerical integration & differentiation
Graphical calculator / GDC (exam mode)
用途: Evaluate a definite integral \(\int_a^b f(x)\,dx\) or a gradient \(f'(x)\) at a point.
使用時機: Checking calculus answers, or where only a numerical value is needed.
步驟
Use the GDC's numeric integral / derivative function with the limits or the point.
考試提示: Allowed under JCQ rules, but you must still show your method — an unsupported calculator answer earns no method marks. Clear all stored programs, notes and data (graphical calculators in exam mode) before the exam.
Statistics & probability distributions
Graphical calculator / GDC (exam mode)
用途: 1-var/2-var statistics, linear regression, and cumulative binomial / normal / Poisson probabilities without tables.
使用時機: Statistics questions and hypothesis tests.
步驟
Enter data in the statistics editor, or use the distribution menu (binomial cdf, normal cdf, …).
考試提示: Allowed under JCQ rules, but you must still show your method — an unsupported calculator answer earns no method marks. Clear all stored programs, notes and data (graphical calculators in exam mode) before the exam.
常見錯誤
1high涉及分數: 4Software Development
Failing to relate comparative technology facts directly to the given scenario context in essay questions.
如何避免: Explicitly mention the users, systems, or entities defined in the prompt (e.g., Rosa's gym, the mobile staff) to justify why a specific system is suitable.
2medium涉及分數: 2Types of Programming Language
Mixing case sensitivity in Little Man Computer (LMC) labels, leading to trace and logic errors.
如何避免: Ensure all variables, mnemonics, and labels strictly match the casing defined in DAT declarations (usually UPPERCASE).
3high涉及分數: 3Structure and function of the processor
Confusing pipelining with parallel processing or multi-core execution.
如何避免: Describe pipelining as overlapping the FDE stages of different instructions to increase throughput, not executing multiple instructions simultaneously on different cores.
4medium涉及分數: 2Boolean Algebra
Incorrectly applying De Morgan's Law by failing to change the operator (OR to AND, or vice-versa) during negation.
如何避免: Remember to change the operator (+ to . or . to +) when negating terms individually: NOT(A OR B) becomes NOT A AND NOT B.
5medium涉及分數: 3Data Types
In floating-point conversions, shifting the binary point in the wrong direction or failing to pad the shifted mantissa with trailing zeros to maintain an 8-bit length.
如何避免: Verify the exponent value direction and pad any shifted mantissa with trailing zeros so it precisely fills the 8-bit size requirement.
6high涉及分數: 2Algorithms
Omit showing the step-by-step overwriting of temporary distances in Dijkstra's/A* algorithm tables.
如何避免: Explicitly draw a strike-through or show updated temporary values in the table to fully document the algorithm's execution state changes.
7medium涉及分數: 3Programming techniques
Writing setter methods or return statements inside procedures, or using inconsistent self-syntax in Object-Oriented coding.
如何避免: Declare setters as procedures (no return value) and getters as functions (must return). Use a consistent pseudocode parameter-naming pattern.