NCEA L1 Digital Tech: Software programming

Software programming in NCEA Level 1 Digital Technologies assesses whether you can turn a problem into a working, tested program and explain the decisions you made. Expect questions on algorithms, control structures, data types, functions, and debugging.

Core rules and concepts

• Every program combines sequence, selection (if/elif/else) and iteration (for/while). Use for when the number of repeats is known; use while when it depends on a condition.
• Declare variables with meaningful names. Know integer, float, string and Boolean. = assigns; == compares.
• A function should do one job, take parameters, and return a value. Variables created inside a function are local.
• Test with normal, boundary and invalid data. Record expected versus actual output.
• Debug by reproducing the fault, isolating the line, and changing one thing at a time.

Worked example

A function must return the average of a list of marks, or None if the list is empty.

def average(marks):
    if len(marks) == 0:
        return None
    total = 0
    for mark in marks:
        total += mark
    return total / len(marks)

Reasoning: the empty-list check prevents division by zero; the loop accumulates; division after the loop gives a float. Test [], [5], [2, 4] and a list containing 0.

Traps

• Off-by-one errors in range() and list indexes.
• Using integer division when a decimal average is required.
• Printing inside a function instead of returning.
• Changing a list while iterating over it.
• Claiming code is correct without evidence from tests.