9-10 Digital Technologies: Designing and validating algorithms Hangman

The 22 key terms

1flowchart

A visual diagram that maps a program's logic before coding, using ovals for start/end, rectangles for steps, and diamonds for yes/no decisions

2decision diamond

A diamond shape in a flowchart that holds a yes/no question. One arrow labelled Yes and one labelled No lead to different steps, and the paths can join up again later.

3chained decisions

Putting one decision diamond after another, so a No arrow leads to the next diamond. This lets a flowchart choose between three or more paths, and every path reaches End.

4flowchart loop

An arrow that goes back to an earlier shape, usually from a decision diamond, so the steps repeat until the exit condition is met and the exit arrow is followed.

5truth table

A table that lists every combination of true and false inputs and shows the result of AND, OR or NOT for each one. Two inputs give four rows.

6age >= 13 AND has_permission = Yes

A combined condition in one decision diamond. AND needs both parts true, OR needs just one, NOT reverses it. One diamond with AND matches two diamonds in a row.

7NOT (A AND B) = (NOT A) OR (NOT B)

De Morgan's law: to negate a compound condition, negate each part and swap AND for OR. Likewise NOT (A OR B) = (NOT A) AND (NOT B). A truth table can prove they match.

8pseudocode

A way of writing algorithms using plain English and common symbols without the rules of any specific programming language, used to plan logic before coding begins

10input

A VCAA pseudocode keyword that accepts a value from the user and stores it in a named variable. Example: input age stores the user's entered value in the variable age

11print

A VCAA pseudocode keyword that outputs a value, variable or expression as a result. Example: print area displays the current value stored in the variable area

13AND

A VCAA pseudocode boolean operator that combines two conditions. The overall result is true only when BOTH conditions are true. Example: x > 0 AND x < 10

14end if

The closing keyword that ends an if-then block in VCAA pseudocode. Every if block must be closed with end if at the same indentation level as the opening if keyword

15IF-THEN-ELSE

A selection structure that runs one set of instructions if a condition is true, and a different set if it is false

16ELSE IF

A keyword that adds another condition to check if the previous IF or ELSE IF condition was false

17FOR i FROM 1 TO n

A loop that repeats its instructions a fixed number of times, counting the variable i from 1 up to n

18WHILE condition DO

A loop that repeats its instructions for as long as the given condition remains true, checked before each repetition

19REPEAT ... UNTIL condition

A loop that repeats its instructions and checks the condition after each repetition, so the body always runs at least once

20flowchart to steps

Changing a flowchart into written steps: a diamond becomes IF or a loop condition, a back arrow becomes REPEAT, then check both versions do the same thing.

21Trace table

A table that records the value of each variable at every step of an algorithm, used to check its logic by hand.

22test case

A chosen input paired with the output you expect. Run the algorithm, record the actual output, then compare: if actual matches expected it passes, otherwise it fails.

23normal, boundary and invalid data

A good test set uses normal data (typical values), boundary data (values at the edges of a range) and invalid data (values that should be rejected), so every path in an algorithm is checked.

24bug

A mistake in an algorithm. Follow the steps until the result goes wrong, then fix that step. It might be in the wrong order, missing, or unclear.