IB MYP Sciences: Key concepts in MYP Sciences – Revision Notes

These revision notes condense the key concepts of IB MYP Sciences for the final weeks before assessment. For full explanations and worked examples, read the key concepts study guide first. The notes follow the IB MYP Sciences guide (for use from September 2014/January 2015; published May 2014, updated May 2019), and suit MYP years 4 and 5 (there is no SL/HL split).

MYP has no prescribed content list – schools design their own units – but the key and related concepts are prescribed, and teachers must plan with them. Test yourself afterwards with the key concepts practice questions. Course hub: /boards/ib/ib-myp/myp-sciences/. Printable checklist: /checklists/ib/ib-myp/myp-sciences/.

Core definitions

• Concept: a lasting “big idea” whose importance reaches beyond one topic, place or time.
• Key concept: a broad concept that works within and across subjects. There are sixteen in the MYP.
• Sciences key concepts: change, relationships and systems.
• Other key concepts the guide says can matter in sciences: development, time, place and space, and creativity.
• Related concept: a narrower, discipline-based concept used to explore a key concept in more depth (for example energy, models, evidence).
• Global context: the real-world setting that shows why the inquiry matters. There are six.
• Statement of inquiry: one sentence that sets the conceptual understanding in a global context.
• Inquiry questions: factual, conceptual and debatable questions drawn from the statement of inquiry.

The three sciences key concepts at a glance

Key concept	What it means in sciences	Words to use
Change	The difference in a system’s state when observed at different times	qualitative, quantitative, rate; reversible, irreversible, self-perpetuating; cause, process, consequence
Relationships	Connections among variables, found by observation or experiment and testable by experiment	variable, correlation, proportional, form and function, model
Systems	Sets of components that function because they are interdependent or complementary	component, interdependent, open, closed, static, dynamic, simple, complex

Change: two ways to classify

By what changes

• Qualitative: structure, behaviour or level changes. Example: a caterpillar becomes a butterfly.
• Quantitative: a number or rate changes. Example: the count rate from a radioactive source falls over time.

By whether it can go back

• Reversible: sugar dissolves in water and can be recovered by evaporating the water.
• Irreversible: a cake bakes; an iron nail rusts.
• Self-perpetuating: the change drives more of itself. A forest fire spreads because burning releases heat that ignites the next trees.

Relationships: three things to say

1. Name the variables and describe the pattern (increases, decreases, proportional, levels off).
2. Give a scientific reason for the pattern.
3. Say how you could test it by experiment, changing one variable and controlling others.

Form and function is a special relationship: link a feature (form) to what it does (function). Examples:

• Biology: a fish’s gills have many thin filaments – a large surface for absorbing oxygen from water.
• Chemistry: powdered zinc reacts faster with acid than a lump – more surface area for collisions.
• Physics: a heat sink has many thin metal fins – a large surface for transferring energy to the air.

Modelling represents relationships that are too large, too slow or too data-heavy to observe directly: for example, how a disease spreads through a population, or how a star changes over millions of years.

Systems: open or closed

	Guide’s meaning	Example
Closed system	Resources are not removed or replaced	A sealed jar with a burning candle: no new oxygen enters, so the flame goes out
Open system	Necessary resources are renewed regularly	A river: water, sediment and organisms flow in and out

Models often use closed systems to simplify or limit variables. Further examples of systems: the digestive system (organs depend on each other), the Earth–Moon system (gravity links the parts), a fuel cell (fuel, oxygen, electrodes and electrolyte interact).

Remember: in later physics and chemistry, “closed” usually means no matter crosses the boundary, though energy can, and “isolated” means neither crosses. Say which meaning you are using.

The other three key concepts

Key concept	Why it matters in science	Example
Development	Scientific knowledge grows through change	Models of the solar system moved from Earth-centred to Sun-centred as evidence built up
Time, place and space	Science defines and measures them	The metre is defined using the speed of light
Creativity	Scientists need imagination to extend understanding	Inventing a new way to measure a quantity you cannot observe directly

Related concepts: the short version

The guide lists twelve related concepts for each of biology, chemistry and physics (and a list for integrated or modular courses that matches the biology one).

	Related concepts
In all three sciences	consequences, energy, evidence, form, function, interaction, models, movement, patterns
Biology adds	balance, environment, transformation
Chemistry adds	balance, conditions, transfer
Physics adds	development, environment, transformation

Teachers may use others, including concepts from other subject groups.

The six global contexts

1. Identities and relationships
2. Orientation in space and time
3. Personal and cultural expression
4. Scientific and technical innovation
5. Globalization and sustainability
6. Fairness and development

Many science units sit naturally in scientific and technical innovation, but courses should give you chances to explore all six over time.

Method in steps: writing a statement of inquiry

1. Pick one key concept (for example relationships).
2. Add one or two related concepts (for example interaction, consequences).
3. Choose one global context (for example identities and relationships, exploring health).
4. Write one sentence that links them and does not name the topic.
5. Test it: would it still be true in a different unit?

Example: Interactions between substances and the body have consequences for health that depend on dose and exposure. This fits units on medicines, alcohol or air pollution.

Method in steps: sorting inquiry questions

The guide’s headings are remembering facts and topics (factual), analysing big ideas (conceptual), and evaluating perspectives (debatable). The tests below are a Marlbridge revision aid.

Type	Test	Example
Factual	Has one right answer you can look up	What is the unit of electrical resistance?
Conceptual	Explains a big idea that transfers to other topics	How does structure determine the properties of a material?
Debatable	Reasonable people disagree; needs evidence and perspectives	Should petrol cars be banned in city centres?

Must-know distinctions

• Key concept vs related concept: change, relationships, systems are key; energy, models, evidence are related.
• Qualitative vs quantitative change: kind of difference vs measured difference.
• Reversible vs self-perpetuating: one can go back; the other feeds itself forward.
• Correlation vs tested relationship: two variables moving together is not enough; a relationship in science can be tested by experiment.
• Open vs closed system: resources renewed vs not removed or replaced.
• Topic vs statement of inquiry: “Photosynthesis” is a topic; a statement of inquiry is a broader idea set in a global context.

Quick self-test

1. Name the three key concepts the guide gives for sciences.
2. Name the three other key concepts the guide says can also be important in sciences.
3. Is boiling an egg reversible, irreversible or self-perpetuating?
4. A cooling drink falls from 80 °C to 52 °C in 10 minutes. Calculate the mean rate of temperature change.
5. Is a mountain lake fed by streams an open or a closed system? Give a reason.
6. A cube-shaped model cell has side 3 cm. Calculate its surface area to volume ratio.
7. Is “energy” a key concept or a related concept in MYP sciences?
8. Name two related concepts listed for chemistry but not for physics.
9. Classify: “What is the chemical formula of methane?”
10. Classify: “Should governments fund space exploration over medical research?”
11. Why do scientific models often use closed systems?
12. What is wrong with the statement of inquiry “Magnets attract iron”?

Answers

1. Change, relationships, systems.
2. Development; time, place and space; creativity.
3. Irreversible: the egg proteins change permanently.
4. Fall = 80 − 52 = 28 °C; 28 ÷ 10 = 2.8 °C per minute.
5. Open: water flows in from streams and out again, so its resources are renewed.
6. SA = 6 × 3² = 54 cm²; V = 3³ = 27 cm³; SA:V = 54 : 27 = 2 : 1.
7. Related concept.
8. Any two of balance, conditions and transfer.
9. Factual.
10. Debatable.
11. To simplify the situation or limit the number of variables.
12. It is a topic fact. It has no key or related concept, no global context, and does not transfer to other units.

Where marks are usually lost

• Writing an everyday definition of change (“when something becomes different”) instead of the science one: a difference in a system’s state at two observed times.
• Classifying a change without a reason. “Irreversible” earns more when you add why: new substances form, or structure is permanently altered.
• Describing a relationship with no direction (“they are linked”) rather than stating how one variable changes as the other changes.
• Giving a form without its function, or a function without the form that causes it. Both halves are needed.
• Listing the parts of a system without saying how they depend on each other.
• Calling a system closed when matter or resources clearly enter or leave it.
• Naming energy, models or evidence as key concepts.
• Writing a statement of inquiry that names the topic and would not transfer.
• Writing a “debatable” question that has a factual answer.

Official syllabus

These notes are aligned to the IB MYP Sciences guide (for use from September 2014/January 2015; published May 2014, updated May 2019), International Baccalaureate Organization. Your teacher will share the task-specific clarifications for any assessed work.