How Do You Build a Concept Map for HSC Revision?

Two students revise the same Chemistry topic. One fills a page with the words temperature, collisions, activation energy, catalysts, and reaction rate. The other connects those ideas with labelled arrows that explain how changing temperature affects a reaction.

Which student is better prepared for an unfamiliar HSC question?

The second. Their notes show not just which concepts belong together, but why they are connected.

To build a concept map for HSC revision, start with a question, organise the important concepts into a hierarchy, and connect them using labelled arrows that form accurate statements. Then add cross-links between different branches to reveal connections you might otherwise miss.

The aim isn’t to fit everything onto one page. It’s to build a visual explanation of how the ideas in a topic work together.

01What makes a concept map different from ordinary notes?

A concept map is a collection of concepts connected by labelled relationships.

Each connection should communicate a complete idea. For example:

• Temperature – increases → average particle kinetic energy.
• Average particle kinetic energy – affects → the fraction of particles with sufficient energy to react.
• A larger fraction of successful collisions – increases → reaction rate.

Notice that each arrow has a specific meaning.

Compare this with writing temperature – reaction rate. The two concepts are related, but the relationship hasn’t been explained. Does temperature increase the rate? Decrease it? Under what conditions? What causes the change?

A useful concept map answers those questions.

Concept maps, mind maps, and flowcharts

These three formats are useful for different purposes.

A mind map might help you list everything you remember about electricity. A flowchart might show the stages of an electrical experiment.

A concept map goes further. It connects ideas such as potential difference, current, resistance, and electrical power using relationships that explain how the concepts fit together.

Three parts of a useful concept map

Every concept map has three important features.

1. Concepts

These are the individual ideas you want to connect.

Examples include:

• Activation energy
• Reaction rate
• Average kinetic energy
• Concentration
• Collision theory

Each concept should be short enough to understand at a glance.

2. Hierarchy

Concepts should be arranged from broader ideas to more specific ones.

For example:

• Chemical reactions
  • Reaction rates
    • Collision theory
      • Successful collisions
        • Sufficient energy
        • Suitable orientation

This arrangement helps you see which ideas are foundational and which depend on them.

3. Cross-links

Cross-links connect concepts from different branches of the map.

These are particularly valuable for HSC revision because exam questions often require you to combine ideas rather than recall one isolated definition.

For example, understanding reaction rates involves Chemistry, but explaining why temperature changes particle motion also draws on Physics. Interpreting a concentration-time graph requires mathematical understanding of gradients.

A cross-link makes those connections visible.

02How to build a concept map in six steps

You don’t need to start with a blank page and immediately know where everything belongs. Build the map in stages.

Step 1: Start with one specific question

Choose a question that the concept map should answer.

Avoid starting with something enormous, such as:

• Everything in HSC Physics
• All of Organic Chemistry
• The entire Mathematics Advanced course

These topics contain too many relationships to organise meaningfully on one page.

Instead, choose a focused question:

• Why does increasing temperature increase reaction rate?
• How are electric fields related to electric potential?
• How do derivatives help describe changing motion?
• How are equilibrium position and reaction conditions connected?

A good focus question gives your map a purpose.

For example, if you’re studying reaction rates, your focus question could be:

Why does changing the temperature, concentration, or presence of a catalyst affect reaction rate?

Every concept you include should help answer that question.

Step 2: Identify the important concepts

Collect the main concepts needed to answer your question.

Use your class notes, textbook, worked examples, and the current NESA syllabus for your course as starting points. The NESA syllabus website is useful for checking the content and terminology relevant to your subject and cohort.

For a focused map, start with approximately 8-12 important concepts.

Don’t copy entire paragraphs into boxes. Extract the actual ideas.

For example, a set of Chemistry notes about reaction rates might contain several pages of explanations. You could reduce the central ideas to:

• Reaction rate
• Collision theory
• Activation energy
• Temperature
• Average kinetic energy
• Concentration
• Catalyst
• Successful collisions
• Concentration-time graphs

You can add smaller details later.

The important thing is to identify the concepts before worrying about their positions on the page.

Step 3: Arrange concepts into a hierarchy

Now decide which ideas are broader and which are more specific.

Place the central concept near the top or centre. Arrange its supporting concepts around or underneath it.

For example:

Reaction rate

• How reaction rate is measured
• Collision theory
  • Successful collisions
  • Activation energy
  • Particle orientation
• Factors affecting reaction rate
  • Temperature
  • Concentration
  • Catalysts

This is a starting structure, not the finished map.

The hierarchy should reflect how the concepts relate logically, rather than simply copying the order in which your teacher covered them.

A useful test is to ask:

Could I explain the smaller concept without understanding the larger one?

If a concept depends on another, the more foundational idea will usually sit higher in the hierarchy.

Step 4: Connect concepts using labelled arrows

This is where your concept map becomes genuinely useful.

Draw arrows between related concepts and label each arrow with a phrase that explains the relationship.

Useful linking phrases include:

For example:

Temperature - increases → average kinetic energy

A catalyst - provides → an alternative reaction pathway

The gradient of a concentration-time graph - represents → the rate of concentration change

Avoid vague labels such as related to, connected with, or affects unless you genuinely cannot specify the relationship more precisely.

A good arrow should allow you to read the two concepts and their connecting phrase as a complete sentence.

Step 5: Add cross-links between different branches

This is often the step that makes the biggest difference.

Look at your existing branches and ask whether a concept in one branch helps explain something in another.

For example, a Chemistry map about reaction rates might have:

• A branch explaining temperature and particle movement.
• A branch explaining collision theory and activation energy.
• A branch explaining how reaction rate is measured using graphs.

You can connect these branches using concepts from Physics and Mathematics.

A cross-link might connect:

Average kinetic energy - influences → successful collisions

Another might connect:

Concentration-time graph - uses its gradient to determine → reaction rate

These connections help you understand the same physical or chemical process from different perspectives.

Don’t force cross-links just to make the map look complicated. Each one should add a meaningful explanation, comparison, or relationship.

Step 6: Check the accuracy of every connection

A concept map can look convincing while containing incorrect relationships.

This is particularly dangerous because an incorrect arrow can become something you repeatedly memorise.

Before considering your map finished, read every connection as a sentence.

For example:

A catalyst - increases → temperature

Does this statement accurately describe what a catalyst does?

No. A catalyst provides an alternative reaction pathway with a lower activation energy. It doesn’t increase the temperature of the reaction mixture.

Correcting individual relationships is just as important as including the right concepts.

We’ll look at a more systematic accuracy check shortly.

04A second example: Connecting Mathematics and Physics

Concept maps aren’t just useful for Chemistry.

Consider the question:

How does a position-time graph help us understand an object’s motion?

You can connect mathematical ideas about gradients and functions to physical quantities such as velocity and acceleration.

Step 1: Start with the broad concept of motion.

Motion can be described by tracking an object’s position as time changes.

Step 2: Add the mathematical relationships.

A position-time graph plots position against time.

Its gradient represents velocity.

In mathematical terms, if position is represented by \(x\), time by \(t\), and velocity by \(v\):

\[ v=\frac{dx}{dt} \]

The derivative of position with respect to time gives velocity.

Step 3: Add acceleration.

Acceleration describes the rate of change of velocity.

If acceleration is represented by \(a\):

\[ a=\frac{dv}{dt} \]

This means acceleration is related to how the gradient of a position-time graph changes.

Step 4: Add the cross-link.

Connect the Mathematics concept of differentiation to the Physics concept of velocity.

Your map could contain:

• Position-time graph – plots → position against time.
• Gradient of position-time graph – represents → velocity.
• Changing gradient – indicates → acceleration.
• Derivative of position – gives → velocity.
• Derivative of velocity – gives → acceleration.

Here’s a common mistake worth catching.

Students sometimes write:

Gradient of position-time graph - represents → acceleration

That’s incorrect.

The gradient represents velocity. Acceleration is related to the rate at which that gradient changes.

This distinction is particularly useful when HSC questions combine graph interpretation with equations of motion.

A good concept map makes it harder to confuse quantities that are related but not interchangeable.

05How do you check whether your concept map is accurate?

Don’t assume that a map is correct just because the individual concepts are familiar.

Check the relationships themselves.

There are five useful tests.

1. Read every arrow as a sentence

Take each connection and read it from left to right.

For example:

Activation energy - is the minimum energy required for → a reaction pathway

This is a meaningful statement.

Compare it with:

Activation energy - related to → temperature

The second statement is too vague to demonstrate understanding.

You should be able to explain precisely how the two concepts interact.

2. Check whether the arrow points in the correct direction

Relationships are not always reversible.

For example:

Increasing temperature - increases → average kinetic energy

You cannot automatically reverse this to claim that increasing average kinetic energy always means you have increased the temperature of the entire system.

Similarly:

Gradient of a position-time graph - represents → velocity

Does not mean velocity represents the gradient of every type of graph.

The axes determine what the gradient means.

3. Check whether the relationship needs a condition

Some relationships are only true under particular conditions.

For example:

Increasing concentration - increases → reaction rate

This is a useful general collision-theory relationship for a simple reaction under suitable conditions, but the actual rate law depends on the reaction mechanism.

A more careful map might say:

Increasing reactant concentration - generally increases → collision frequency

You can then explain how collision frequency influences reaction rate.

Adding the appropriate conditions prevents you from memorising statements as universal rules when they aren’t.

4. Look for tempting but incorrect relationships

Try to identify statements that sound reasonable but aren’t quite right.

Consider these examples:

These errors are particularly useful to catch because they can survive even when you know the individual definitions.

5. Verify the relationships against reliable material

Use your current syllabus, class notes, textbook, and worked examples to check important claims.

Pay particular attention to:

• Definitions and conditions.
• Equations and the meaning of each variable.
• Graph gradients and what they represent.
• Cause-and-effect relationships.
• Assumptions behind simplified models.

If you cannot verify a connection, don’t simply leave it in the final map because it looks plausible.

Mark it for checking and resolve it before relying on the map for revision.

A concept map doesn’t need to be perfect on the first attempt. Correcting an inaccurate relationship is part of the learning process.

06How should you use concept maps for HSC revision?

Building the map is only the first part. You also need to use it to test whether you can recall and explain the connections.

A useful approach is:

1. Build the first version from memory.

After learning a topic, close your notes and write down the important concepts you can remember.

Try to organise them into a hierarchy and connect them without looking at the textbook.

2. Check what you’ve missed.

Compare your map with your notes and syllabus.

Look for missing concepts, incorrect arrows, and relationships you couldn’t explain.

3. Rebuild the difficult sections.

You don’t need to redraw the entire map every time.

If you struggle to connect activation energy and temperature, revisit that particular relationship and make sure you understand the underlying explanation.

4. Use the map to answer unfamiliar questions.

Choose an exam-style question that combines two or more concepts.

Before attempting it, identify the relevant connections on your map.

Then solve the question without simply copying the map’s wording.

5. Update the map when you discover a gap.

If a worked solution reveals a relationship you hadn’t considered, add it.

For example, if you initially understood that temperature increases reaction rate but couldn’t explain why the activation energy remains unchanged, add that distinction.

This turns your map into a record of the relationships you actually need to understand.

Concept maps work particularly well alongside active recall. Simply rereading notes can make material feel familiar without proving that you can retrieve and apply it. You can read more about this in Why Rereading Notes Feels Better Than It Works.

For calculation-heavy subjects, also practise applying the relationships in unfamiliar problems. A map might remind you which principle applies, but you still need to select the correct equation, substitute the values, and interpret the result. See How to Learn from Worked Solutions Without Copying Them for a useful approach.

07Questions and solutions

Use these questions to test whether you can construct, interpret, and evaluate concept maps rather than simply describe their features.

Question 1

A student is constructing a concept map about uniform motion. They have identified four concepts:

• Position
• Time
• Gradient
• Velocity

Write two labelled connections that would form accurate statements. Identify which connection provides a useful link between Mathematics and Physics.

Solution 1

The key cross-topic connection is:

Gradient of a position-time graph - represents → velocity

This connects a mathematical property of a graph to a physical quantity describing motion.

The second connection could be:

Position-time graph - plots → position against time

Together, these relationships explain how a graph can be used to determine velocity.

The gradient tells us how quickly position changes as time passes. In Physics, this rate of change is velocity.

Simply connecting the words gradient and velocity with an unlabelled line would not demonstrate this understanding. The labelled relationship explains exactly what the gradient represents.

Question 2

A student creates a concept map about reaction rates with the following relationships:

• Temperature – increases → activation energy.
• Activation energy – increases → reaction rate.

Both arrows are incorrect.

Rewrite the map as a chain of at least four accurate labelled relationships. Include one connection to Physics and explain why activation energy does not increase simply because temperature increases, assuming the reaction pathway remains unchanged.

Solution 2

The correct chain is:

Temperature - increases → average particle kinetic energy

Higher average kinetic energy - increases → fraction of particles with energy at least equal to activation energy

Greater fraction of sufficiently energetic particles - increases → successful collisions per second

More successful collisions per second - increases → reaction rate

The Physics connection is the relationship between temperature and average particle kinetic energy.

The original map incorrectly suggests that heating increases activation energy.

Activation energy is a property of the reaction pathway. If the pathway remains unchanged, its activation energy remains unchanged when temperature increases.

Instead, increasing temperature changes the distribution of particle energies. More particles have enough energy to overcome the existing activation energy.

This distinction is important because increasing temperature and adding a catalyst can both increase reaction rate, but they achieve this through different mechanisms.

Question 3

A student is analysing a position-time graph.

Over a particular interval, the curve has a negative gradient that becomes progressively more negative.

The student’s concept map contains the relationship:

Steeper position-time curve - means → greater acceleration

Explain why this relationship is incomplete or incorrect.

State:

• Whether the object’s velocity is positive or negative.
• Whether its speed is increasing or decreasing.
• Whether its acceleration is positive, negative, or zero.

Rewrite the incorrect relationship using two accurate labelled connections.

Solution 3

The object has negative velocity, increasing speed, and negative acceleration.

The original relationship is incorrect because the gradient of a position-time graph represents velocity, not acceleration.

The two correct connections are:

Position-time graph gradient - represents → velocity

Change in position-time graph gradient - indicates → acceleration

Here’s how to interpret the information.

Velocity: The gradient is negative, so the object’s velocity is negative. This means its position is decreasing in the chosen positive direction.

Speed: The gradient becomes more negative, so its magnitude increases. The object is moving faster.

Acceleration: Velocity is becoming increasingly negative. Therefore, its rate of change is negative, meaning the acceleration is negative.

The important distinction is that the steepness of a position-time graph tells you the magnitude of velocity. Acceleration depends on how that gradient changes over time.

A map that connects gradient directly to acceleration would cause errors when interpreting motion graphs.

Question 4

A chemical reaction occurs at constant temperature, and its reaction pathway remains unchanged.

As the reaction proceeds:

• The concentration of a reactant decreases.
• The concentration-time graph becomes progressively flatter.
• The reaction rate decreases.

A student’s concept map contains the following chain:

Lower reactant concentration - increases → activation energy - causes → slower reaction rate

Identify the incorrect relationship and construct a more accurate chain connecting reactant concentration, collision theory, and the shape of the concentration-time graph.

Explain which quantities remain unchanged under the stated conditions.

Solution 4

The activation energy does not increase. The reaction rate decreases because fewer reactant particles are available to collide successfully per unit time.

The corrected chain is:

Lower reactant concentration - reduces → collision frequency

Lower collision frequency - reduces → successful collisions per second

Fewer successful collisions per second - decreases → reaction rate

Lower reaction rate - produces → smaller magnitude of the concentration-time graph gradient

The activation energy remains unchanged because the reaction pathway has not changed.

Temperature is also constant, so the particle energy distribution remains unchanged.

As reactants are consumed, fewer reactant particles are present per unit volume. This reduces the number of collisions and, consequently, the number of successful collisions per second.

The concentration-time graph becomes flatter because the reactant concentration is changing more slowly.

There is an important mathematical detail here. The gradient of the reactant concentration-time graph is negative, but its magnitude becomes smaller as the reaction slows.

The student’s original map incorrectly attributes the decreasing rate to an increasing activation energy. The actual explanation comes from changing reactant concentration and collision frequency.

Question 5

A reversible reaction is exothermic in the forward direction.

Two identical closed systems begin with the same initial composition, containing reactants but no products. Both systems are kept at fixed volume.

Two different changes are made:

• System A: The temperature is increased. No catalyst is added.
• System B: A catalyst is added, but the original temperature is maintained.

The amount of catalyst in System B is chosen so that both systems have the same measured initial forward reaction rate.

Both systems are then allowed to reach equilibrium.

A student proposes the following concept-map relationships:

1. Same initial reaction rate – means → same collision mechanism.
2. Same initial reaction rate – means → same final equilibrium composition.
3. Higher temperature – increases → successful collisions.
4. Catalyst – increases → successful collisions.

Evaluate all four relationships.

Then construct a corrected concept map that explains:

• Why the initial rates can be equal even though the mechanisms differ.
• Why the two systems do not necessarily reach the same equilibrium composition.
• What concentration-time measurements would reveal about the difference between the systems.

State any important assumptions in your explanation.

Solution 5

The two systems can have the same initial reaction rate but different particle-level mechanisms and different final equilibrium compositions.

The crucial distinction is between reaction kinetics, which describes how quickly a reaction proceeds, and chemical equilibrium, which describes the final balance between forward and reverse reactions.

Relationship 1: Same initial rate means the same collision mechanism.

Incorrect.

The initial rate is a macroscopic measurement. It tells us how quickly the reactant concentration is initially changing.

It does not uniquely identify the microscopic mechanism responsible for that rate.

In System A, increasing temperature raises average particle kinetic energy. A greater fraction of particles have sufficient energy to overcome the activation energy.

In System B, the catalyst provides an alternative reaction pathway with a lower activation energy. The average particle kinetic energy does not increase.

Both changes can increase the number of successful collisions per second, but they do so differently.

Relationship 2: Same initial rate means the same final equilibrium composition.

Incorrect.

Equal initial rates tell us nothing definitive about whether the two systems will reach the same equilibrium composition.

System A has a higher temperature. Because the forward reaction is exothermic, increasing temperature favours the reverse, endothermic direction at equilibrium.

Therefore, the equilibrium position shifts towards the reactants.

System B has a catalyst but remains at its original temperature.

A catalyst increases the rates of both the forward and reverse reactions. It does not change the equilibrium constant or the final equilibrium composition.

Consequently, System A and System B will generally reach different equilibrium compositions.

Relationship 3: Higher temperature increases successful collisions.

Correct, with an important qualification.

Higher temperature increases average particle kinetic energy and the fraction of particles with sufficient energy to overcome activation energy.

This increases the number of successful collisions per second.

Relationship 4: A catalyst increases successful collisions.

Correct.

The catalyst provides an alternative pathway with lower activation energy.

A greater fraction of collisions can therefore lead to reaction at the same temperature.

The catalyst does not increase average particle kinetic energy.

Constructing the corrected map

The two branches should be represented separately.

For System A:

Higher temperature - increases → average particle kinetic energy

Higher average kinetic energy - increases → fraction of particles above activation energy

Greater fraction above activation energy - increases → successful collisions per second

Higher temperature - shifts → equilibrium towards reactants for an exothermic forward reaction

For System B:

Catalyst - provides → alternative reaction pathway

Alternative pathway - has → lower activation energy

Lower activation energy - increases → fraction of successful collisions

Catalyst - changes → reaction rates without changing equilibrium composition

The two branches share an initial observation:

More successful forward collisions per second - produces → higher initial forward reaction rate

But this does not mean they share the same mechanism or equilibrium position.

How could you distinguish the two systems experimentally?

Measure reactant or product concentrations over time in both systems.

The initial concentration-time gradients can be identical because the initial forward rates have been matched.

However, the curves will generally approach different final concentrations.

System A reaches an equilibrium with a greater proportion of reactants because its higher temperature favours the endothermic reverse reaction.

System B reaches the equilibrium composition associated with the original temperature. Its catalyst changes how quickly equilibrium is reached, not where equilibrium lies.

The assumptions are that the reaction remains reversible, no side reactions occur, both systems are closed, and the catalyst does not alter the reaction’s thermodynamics.

This question demonstrates why a concept map must distinguish between relationships that describe reaction rate and relationships that describe equilibrium.

Two systems can produce the same initial measurement without following the same mechanism or reaching the same final state.

That’s exactly the sort of distinction a well-constructed concept map should help you recognise.

08The main principle to remember

A useful HSC concept map does three things:

1. Organises concepts into a hierarchy, so you can see which ideas are foundational.
2. Uses labelled arrows to explain how individual concepts relate.
3. Includes accurate cross-links that connect different branches, topics, and subjects.

The most important part is the relationship between the concepts, not the number of boxes on the page.

When you can explain every arrow, recognise when a relationship needs a condition, and use the map to solve an unfamiliar problem, you’ve moved beyond memorising isolated facts.

Your next step is to build a small map from memory after studying a topic, then test it against an HSC question that requires you to combine at least two of its concepts.