Course Toolkit

Flowcharts

A flowchart shows the steps of an algorithm with shapes and arrows. An algorithm is a step-by-step plan for solving a problem.

The syllabus asks you to represent algorithms with flowcharts in mechatronic systems, games and apps.

The shapes

• Terminator (rounded ends): START at the top and END at the bottom.
• Process (rectangle): one action or calculation, such as “Add 1 to count”.
• Decision (diamond): a yes or no question. Both exits are labelled Yes or No.
• Input or output (parallelogram): data coming in, such as “Input age”, or going out.
• Subprogram (rectangle with a line down each side): a named task done elsewhere.

Arrows show the order. START has one arrow out. END can have more than one arrow in, because two paths can finish at the same END.

How to draw one, step by step

1. Write the steps in plain words, in order.
2. Draw START at the top and END at the bottom.
3. Turn each step into a shape. Use a rectangle for an action and a diamond for a question.
4. Join the shapes with arrows that follow the order.
5. Label both exits of every decision Yes or No.

Pseudocode

Pseudocode writes an algorithm as short, plain-English lines. It is not a real programming language, so a computer cannot run it. Its job is to help people follow the logic before they write code.

Use the same few keywords every time. Write keywords in capitals, put one step on each line, and indent the lines inside an IF or a loop.

Here is the club check, written three ways. Each row matches one flowchart shape to its pseudocode and Python lines.

# The club check, written in Python
age = int(input("How old are you? "))   # input() gives text, so int() makes it a whole number
if age >= 13:
    print("You can join the club")
else:
    print("Sorry, you need to be 13 or older")

Worked example: counting down from 3 with a loop. The loop repeats while count is more than 0.

SET count TO 3
WHILE count > 0
    OUTPUT count
    SET count TO count - 1
END WHILE
OUTPUT "Go!"

The loop outputs 3, then 2, then 1. When count becomes 0, the loop stops and “Go!” is output. The full output is 3, 2, 1, Go!

IPO charts

An IPO chart is a planning table with three columns: Input, Process and Output. Before a program is written, you list what goes in, what the program does with it, and what comes out.

The Creating games and simulations focus area names IPO charts as a development tool, so they are useful when you design a game.

How to make one, step by step

1. Write the task in one sentence.
2. List every input: data the user types, and values the program already holds.
3. List the process: the steps that turn the inputs into the output, in order.
4. List the output: what the user sees or receives.
5. Check that someone could build the program from the chart alone.

The price is an input even though the buyer never types it. Inputs can be typed in, or stored in the program.

Decision trees

A decision tree starts with one question at the top. Each answer follows a branch down to the next question, or to an outcome at the end of the path. A decision tree shows every path a program could take, so you can check that none are missing.

Think of it as a flowchart that only asks questions. Every branch moves forward and ends in an outcome, so there are no loops.

How to draw one, step by step

1. Write the first question at the top, in a box.
2. Draw a branch for each answer, and label every branch Yes or No.
3. At the end of each branch, put the next question in a box, or write the outcome if no more questions are needed.
4. Keep going until every path ends in an outcome.

Enrolled at this school?
  No  -> Not allowed to borrow a laptop
  Yes -> Returned the last laptop on time?
           No  -> Return the old laptop first
           Yes -> Is a laptop free?
                    No  -> Join the waiting list
                    Yes -> Borrow a laptop

Storyboards and wireframes

A storyboard is a set of numbered frames. Each frame shows one moment: what the screen or scene looks like, what the user does, and what happens next. Designers use storyboards to plan an animation or a game before they build it. A storyboard is also a common tool for planning screens in any focus area, such as an app or a website.

A wireframe is a simple layout sketch of one screen. It uses plain boxes with labels, such as Title, Image or Button. It has no colours and no real content, so people can focus on where things go. A prototype is a trial model that tests an idea before the final product is built. It can be a paper sketch or a clickable digital mock-up.

How to make a storyboard, step by step

1. Write the story or task in one sentence.
2. Draw four to six numbered boxes, one for each moment.
3. In each box, sketch the screen or describe the scene.
4. Under each box, write what the user does and what happens next.
5. Read the frames in order, as the user would. Does the story flow smoothly?

Trace tables and desk checking

A trace table records the value of each variable at each step of an algorithm. Desk checking means checking an algorithm by hand, on paper, before you run it. NESA’s glossary describes tracing as following an algorithm to check its logic and correctness, using a sample of typical inputs.

A variable is a labelled box that stores a value, such as total.

How to trace, step by step

1. Make one column for each variable, and one for the output.
2. Write the starting values in the first row.
3. Work through each line in order. When a value changes, write the new value in the next row.
4. For a loop, write one row each time round the loop.
5. Compare the final output with what the task says it should be.

SET total TO 0
SET count TO 0
FOR EACH score IN (4, 7, 2)
    SET total TO total + score
    SET count TO count + 1
END FOR
OUTPUT total / count

The output is 13 ÷ 3, which is about 4.33. The trace shows the algorithm gives that answer for this sample.

Test cases and test data

A test case is a plan for one check of a program. It has three parts: the test data you type in, the expected output (what should happen), and the actual output (what really happens). If they match, the test passes.

Every focus area asks for test cases. There are three kinds of test data:

• Typical: normal data, such as 15 for an age.
• Boundary (edge): values on a limit, such as 12 and 13 for “13 or older”.
• Invalid: data the program should reject, such as “twelve”.

How to write test cases, step by step

1. Take each rule, such as “13 or older can join”.
2. Write one typical test, then boundary tests: the limit and the value just below it.
3. Write invalid tests: wrong types, or values the rules do not allow.
4. Write the expected output first, then mark each test Pass or Fail.

Test 2 and Test 4 showed the two faults. This fixed version handles both. Run all four tests again.

text = input("How old are you? ")
if not text.isdigit():                # digits only (also rejects negatives)
    print("Please type a whole number")
else:
    age = int(text)
    if age >= 13:                     # fixed: 13 is now allowed
        print("You can join the club")
    else:
        print("Sorry, you need to be 13 or older")

Use cases and requirements

A requirement is something a solution must do, or must be like. Before anyone builds a program, the people who will use it agree on its requirements. There are two kinds:

• Functional requirements say what the solution must do, such as “shows each student’s due date”.
• Non-functional requirements say how well it must work, such as how fast, easy, safe or private it is.

A use case describes one thing a user does with a solution, step by step. It names the actor (the user or device), the goal and the main steps.

How to write a use case, step by step

1. Name it with a short verb phrase, such as “Borrow a book”.
2. Name the actor and the goal.
3. List the main steps in order, showing what the user does and what the system does.
4. Add what happens if something goes wrong.

Requirements for the library app:

Network maps and sociograms

A network map shows devices or people as dots, and the connections between them as lines. In a network map, each dot is a node, and each line is a link. A sociogram is a network map of people, showing who is linked to whom.

The degree of a node is the number of links that touch it. A path is a route from one node to another, following the links. The shortest path has the fewest links.

How to draw one, step by step

1. List the nodes: each person or device.
2. Draw each node as a labelled circle.
3. For each node, list who or what it is directly linked to.
4. Draw one line for each link. Do not draw the same link twice.
5. Count the degree of each node, then trace paths along the lines.

Chloe has the highest degree, so she is the best connected person in this group. The path from Ava to Ella is Ava, Chloe, Dev, Ella: 3 links. The longer route through Ben has 4 links.

Spreadsheets

A spreadsheet is a grid of cells. Each cell has a column letter and a row number, such as B3 (column B, row 3). That address is the cell reference. A range is a block of cells, written with a colon: C2:C6 means cells C2 down to C6.

A formula starts with an equals sign and uses functions, listed here.

Made-up sports day list:

How to use one, step by step

1. Type a heading in row 1, and one kind of data in each column.
2. Start a formula with = in an empty cell. Check that the range covers every row.
3. Sort by score, highest first: Ella, Chloe, Ava, Dev, Ben.
4. Filter to one team, such as Blue: Ben and Ella.
5. Use conditional formatting to colour cells that meet a rule, such as scores of 15 or more.
6. Select the names and scores, then insert a column chart.

Menu names differ between programs. Look for Sort, Filter, Conditional formatting and Chart.

Simple SQL

SQL is a language for asking a database questions and changing its data. A database stores data in tables. Each table has records (rows, one for each item) and fields (columns, one for each kind of fact).

The syllabus names SELECT, WHERE, ORDER BY and LIMIT, and asks you to insert and update data. AND, OR and NOT join conditions. FROM, INTO, VALUES and SET complete these statements. DESC and ASC set the order (highest first, or lowest first). The syllabus does not name them, so treat them as an extra. No other keywords appear here.

This is a made-up table called Games.

Worked examples

Query 1: the puzzle games and their prices.

SELECT Title, Price
FROM Games
WHERE Genre = 'Puzzle';

Result: Block Builder (15) and Pixel Pets (10).

Query 2: the three most expensive games.

SELECT Title, Price
FROM Games
ORDER BY Price DESC
LIMIT 3;

Result: Sky Ninja (35), Star Quest (30) and Road Rally (25).

Query 3: non-puzzle games that cost less than $30, in alphabetical order.

SELECT Title
FROM Games
WHERE NOT (Genre = 'Puzzle') AND Price < 30
ORDER BY Title ASC;

Result: Dino Dig, then Road Rally. To match either genre instead, use OR: WHERE Genre = 'Adventure' OR Genre = 'Racing' returns Dino Dig, Road Rally and Star Quest.

Query 4: add a game, then change a price.

INSERT INTO Games (GameID, Title, Genre, ReleaseYear, Price)
VALUES (7, 'Ocean Run', 'Racing', 2024, 18);

UPDATE Games
SET Price = 12
WHERE GameID = 2;

Result: the table gets a seventh row, Ocean Run. Block Builder now costs $12, not $15. Without the WHERE line, the UPDATE would change every row.

Data modelling

Data modelling means planning how data will be organised before a database is built. You decide what to store (entities), which facts to keep about each (attributes) and how they link (relationships).

Each table needs a primary key: an attribute whose value is different for every record, such as PlayerID. A foreign key is a field that holds another table’s primary key.

How to model, step by step

1. List the entities. For a sports club, these are Team and Player.
2. List the attributes of each entity, and choose a primary key.
3. Decide how the entities link. One team has many players, but each player is in one team: one-to-many.
4. Put the foreign key on the “many” side. The Player table holds TeamID.
5. Check that each player points to exactly one team.

Team table

Player table

The team name is stored once, in the Team table, not repeated in every player row. If it changed, only one row would need changing.

Data types and validation

A data type tells the computer what kind of value a field or variable holds. The right type stops mistakes. For example, you cannot add up names.

Names vary between programs, so these are the common names. A phone number should be a string. 0412 345 678 starts with a zero, and an integer would lose that zero.

Validation checks that data is sensible before the program uses it. The main checks are:

text = input("Enter the score: ")
if text == "":                        # presence: something was typed
    print("Please type a score.")
elif not text.isdigit():              # type: digits only, so a minus sign is also rejected
    print("Scores must be whole numbers.")
elif int(text) > 100:                 # range: 100 is the largest allowed
    print("Scores must be 100 or less.")
else:
    print("Score accepted:", int(text))

Each check in the code matches a row of the table. Try nothing typed, then “abc”, “150” and “42”. They give the presence, type and range messages, and then “Score accepted: 42”.