Card 21: Exam Technique

Module 7: Expert Techniques

1 The Examiner's Secret

Examiners don't read every line of code. They look for Marking Points.

IPO + Loop is the magic formula for 6-mark questions:

Input (Ask for data) - 1 Mark
Process (Do the math/logic) - 2 Marks
Output (Show the result) - 1 Mark
Loop (Repeat until done) - 1-2 Marks

2 Worked Example

"Write an algorithm to calculate ticket prices." (6 Marks)

# 1. INPUT (1 Mark)

tickets = int(input("How many tickets? "))

# 2. PROCESS (Calculation) (1 Mark)

price = tickets * 10

# 3. PROCESS (Selection/Logic) (1 Mark)

if tickets > 5:

price = price * 0.9 # Discount

# 4. OUTPUT (1 Mark)

print("Total: " + str(price))

PREDICT: Mark This Code

A student wrote this for a "Positive Number" check. How many marks (out of 3)?

num = input("Enter num: ")
if num > 0:
print("Positive")

BRONZE (DEBUGGING)

🥉 The Broken Logic

Examiners love "Off By One" errors or incorrect logic operators.
This code should loop while number is NOT 10.
But it uses or instead of != (or similar logic). Fix it.

bronze.py

num = 0
# BUG: This loop logic is wrong.
# It should loop until num IS 10.
while num < 10 or num > 10:
    num = int(input("Enter 10 to stop: "))
print("Success")

> _

SILVER (TRACE)

🥈 Predict the Output

Examiners ask you to "Trace" loops. Predict what total will be.
Task: Run the code and see if you were right. (Correct answer is printed).

silver.py

total = 0
x = 1
while x < 5:
    total = total + x
    x = x + 1

print("Total is: " + str(total))

> _

GOLD (EXAM QUESTION)

🥇 The 6-Mark Algorithm

Question: Write a program that asks for a Password.
- It must be longer than 5 letters (Validation).
- It must NOT be "password" (Security).
- Keep asking until valid.
- Print "Access Granted" at the end.

gold.py

pw = input("Enter password: ")

# VALIDATION LOOP
while ...:
    print("Invalid")
    # Don't forget to ask again!
    pw = ...

print("Access Granted")

> _