IGCSE Computer Science Paper 2 Definitions Worksheet: 7d Standard Methods of Solution and 8.1a Data Types and Variables (Modules 307–316)
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Key terms
Write what each term means, in your own words.
1
DECLARE, loop, OUTPUT
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complete the algorithm
3
dry run
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variable
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CONSTANT
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identifier
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case insensitive
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DECLARE Counter : INTEGER
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DECLARE Initial : CHAR
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Counter ← 0
Answer Key
IGCSE Computer Science Paper 2 · Modules 307–316 · Student wording will vary for definitions
1DECLARE, loop, OUTPUT — To solve a described problem, list the inputs, pick the standard method, then write it: DECLARE variables, set start values, loop through the data, and OUTPUT the result.
2complete the algorithm — Fill each missing line or value by asking what the standard method (total, count, max, search, sort) needs at that point: start value, loop bound, condition or closing keyword.
3dry run — Following an algorithm line by line with given data, recording each variable's value in a trace table, to find its output or purpose.
4variable — A named storage location in memory whose value can change while a program runs, such as Score going from 0 to 10. Programs use it to remember values.
5CONSTANT — A named value set once before the program runs that never changes, unlike a variable. Example: CONSTANT Pi ← 3.142 or CONSTANT HourlyRate ← 12.50 are fixed while the program runs.
6identifier — The name of a variable, constant, procedure or function. Use PascalCase: letters and digits only, no spaces or underscores, start with a capital letter, e.g. FirstName.
7case insensitive — Capital letters do not matter in identifiers, so Countdown and CountDown are the same name. Never use names that differ only in case as two separate variables.
8DECLARE Counter : INTEGER — Creates a variable called Counter that can only hold whole numbers. Use DECLARE name : TYPE, with a space either side of the colon, before you use the variable.
9DECLARE Initial : CHAR — DECLARE creates a variable and sets its type. Here Initial can hold one CHAR (a single character). Use : STRING instead for text, e.g. DECLARE FirstName : STRING.
10Counter ← 0 — Assignment: the value on the right of the arrow is stored in the variable on the left. Counter ← 0 stores 0 in Counter and replaces any earlier value.