Volcanic eruptions depend partly on magma composition, viscosity and trapped gas. Low-viscosity magma allows gas to escape and often produces flowing lava, while high-viscosity magma can trap gas and build pressure, increasing the chance of explosive eruptions.
Example
Basaltic magma is usually less viscous than silica-rich magma, so basaltic eruptions often produce long lava flows rather than towering ash columns.
Key terms
Magma:
Molten rock beneath Earth's surface.
Viscosity:
A fluid's resistance to flowing.
Eruption:
Release of magma, gas or ash from a volcano.
Questions
1. Which statement best captures volcanoes: magma, viscosity and eruption style?
Magma viscosity and gas behaviour help explain differences in volcanic eruption style.
All volcanoes erupt in the same explosive way because all magma is identical.
The pattern can only be explained by guessing.
The topic has no observable evidence.
2. Which term means "Molten rock beneath Earth's surface."?
Magma
Viscosity
Eruption
Variable
3. Which term means "A fluid's resistance to flowing."?
Viscosity
Magma
Eruption
Conclusion
4. Which term means "Release of magma, gas or ash from a volcano."?
Eruption
Magma
Viscosity
Prediction
5. Which observation task is most relevant to this topic?
Compare photos and descriptions of shield volcanoes and steep composite volcanoes.
Copy the topic title without looking at an example.
Choose a result before making observations.
Ignore details that do not match a first guess.
6. Which model would best represent the key process or relationship?
Create a cause-and-effect diagram linking composition, viscosity, trapped gas and eruption style.
A decorative drawing with no labels or connection to evidence.
A list of unrelated facts.
A model that deliberately contradicts every observation.
7. Which investigation is focused most directly on the scientific idea?
Time equal volumes of safe liquids with different viscosities moving down the same slope.
Change many uncontrolled factors and record nothing.
Ask only for opinions and treat them as measurements.
Repeat a memorised answer without testing it.
8. Which evidence best supports the lesson explanation?
More viscous liquids flow more slowly, modelling how high-viscosity magma resists movement and can trap gas.
All volcanoes erupt in the same explosive way because all magma is identical.
One preferred answer with no observation.
A claim that cannot be checked in any way.
9. Which task applies the science in a new context?
Use magma and landform evidence to compare likely hazards near two different volcano types.
Write the heading again without explaining it.
Ignore the system and choose randomly.
Assume the same answer fits every situation.
10. Which response best corrects the misconception in this topic?
Magma viscosity and gas behaviour help explain differences in volcanic eruption style.
All volcanoes erupt in the same explosive way because all magma is identical.
Both statements must be equally correct.
Evidence cannot help decide between explanations.
11. What makes a scientific observation useful?
It records relevant details without changing them to fit an expectation.
It includes only details that support a preferred answer.
It replaces measurements with guesses.
It hides the conditions under which it was made.
12. Why should a scientific model include its limitations?
Models simplify reality, so users need to know what the representation leaves out.
A limitation proves the model has no value.
Models are exact copies and never omit anything.
Limitations should be hidden so a model looks certain.
13. What makes a comparative investigation fair?
Change or compare the intended factor while keeping other relevant conditions consistent.
Change every condition at the same time.
Measure only the result that looks best.
Decide the conclusion before collecting data.
14. Why repeat measurements or use several samples?
To reveal variation and reduce the influence of chance or one unusual result.
To guarantee a preferred conclusion.
To make units unnecessary.
To remove the need for a clear method.
15. What is the best response to an anomalous result?
Record it, check the method and investigate whether it is error or meaningful variation.
Delete it automatically.
Delete all other results instead.
Assume it proves the whole topic wrong.
16. Which conclusion is scientifically responsible?
One that answers the question, uses the evidence and states important limits.
One that claims more than the data show.
One that ignores conflicting evidence.
One based only on the expected answer.
17. What would make the claim about volcanoes: magma, viscosity and eruption style stronger?
Several relevant, repeatable evidence lines that agree with the explanation.
A larger heading and no new evidence.
Removing results that are inconvenient.
Relying on a single uncheckable opinion.
18. What should happen if reliable new evidence conflicts with a model?
The model should be reviewed and revised or replaced if needed.
The evidence should always be hidden.
The original model must never change.
Scientists should stop asking questions.
19. How should safety and ethics shape an investigation?
Risks, people, living things and environments should be considered before the method is used.
Safety matters only after data collection.
Any method is acceptable if it is fast.
Ethics has no place in science.
20. What makes science communication trustworthy?
Clear methods, accurate terms, relevant evidence and acknowledgement of uncertainty.
Certainty without evidence.
Leaving out how results were obtained.
Using dramatic language instead of data.
21. What is the strongest overall outcome from studying volcanoes: magma, viscosity and eruption style?
Use observations, models, investigations and evidence to explain and apply this idea.
Memorise the title without using it.
Avoid testing explanations.
Treat every first idea as permanently correct.
Answer key (parent copy)
1. Magma viscosity and gas behaviour help explain differences in volcanic eruption style.
2. Magma
3. Viscosity
4. Eruption
5. Compare photos and descriptions of shield volcanoes and steep composite volcanoes.
6. Create a cause-and-effect diagram linking composition, viscosity, trapped gas and eruption style.
7. Time equal volumes of safe liquids with different viscosities moving down the same slope.
8. More viscous liquids flow more slowly, modelling how high-viscosity magma resists movement and can trap gas.
9. Use magma and landform evidence to compare likely hazards near two different volcano types.
10. Magma viscosity and gas behaviour help explain differences in volcanic eruption style.
11. It records relevant details without changing them to fit an expectation.
12. Models simplify reality, so users need to know what the representation leaves out.
13. Change or compare the intended factor while keeping other relevant conditions consistent.
14. To reveal variation and reduce the influence of chance or one unusual result.
15. Record it, check the method and investigate whether it is error or meaningful variation.
16. One that answers the question, uses the evidence and states important limits.
17. Several relevant, repeatable evidence lines that agree with the explanation.
18. The model should be reviewed and revised or replaced if needed.
19. Risks, people, living things and environments should be considered before the method is used.
20. Clear methods, accurate terms, relevant evidence and acknowledgement of uncertainty.
21. Use observations, models, investigations and evidence to explain and apply this idea.