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Gather & Interpret data
Use evidence
Critique evidence
Interpret representations
Engage with science

Understanding about science
Investigating in science
Communicating in science
Participating and contributing

Living world
Material world
Physical world
Planet Earth and beyond

GNS Science Learning resources

Comparing different versions of the same scale provides an opportunity for students to strengthen their capability to make sense of representations in the context of science.

Curriculum Aims and AOs

NZC LINKS: The Nature of Science strand


Aim	Achievement objectives relevant to this resource
Communicating in Science Develop knowledge of the vocabulary, numeric and symbol systems, and conventions of science and use this knowledge to communicate about their own and other’s ideas.	L4: Engage with a range of science texts and begin to question the purposes for which these texts were constructed. L5: Apply their understandings of science to evaluate both popular and scientific texts (including visual and numerical literacy).

NZC LINKS: Planet Earth and Beyond


Aim	Achievement objectives relevant to this resource
Earth Systems Investigate and understand the spheres of the Earth system: geosphere (land), hydrosphere (water), atmosphere (air), and biosphere (life).	L6: Investigate the external and internal processes that shape and change surface features of New Zealand.

Learning focus

Students compare at least two different versions of the modified Mercalli scale and discuss how and why this particular scale might have been constructed.

Learning activity

The GNS Science webpage on the Modified Mercalli Intensity Scale explains that the version used in New Zealand has been adapted for New Zealand conditions.

Numerous “international” versions of the scale can be found with a quick internet search, most of them also showing minor variations from each other. Choose at least one of these to be compared with the New Zealand specific version.

Adapting the resource

After reading the information on the GNS website, ask students:
- Is the scale is qualitative (descriptive) or quantitative (based on numbers)? [This might cause some debate because the scale descriptors are subsequently converted to numbers – which is a typical feature of qualitative scales used by scientists when communicating with each other.]
- What does the scale describe and why will it vary from place to place? [It measures the felt intensity of the earthquake, and this varies according to distance from the epicentre, nature of the ground in an area, etc.]
Now have students compare the GNS version with another version.
- Ask students to list at least three specific ways in which the GNS version has been modified by New Zealanders’ experiences of earthquakes. [For example, few international examples mention that animals can show alarm – why might that be?]
- Ask who might want to use this scale – and why is it important that there is one agreed version to use in New Zealand? [For example, an insurance company might want to base decisions about earthquake risks to buildings on historical effects in an area, or in similar areas. They can’t just make up a scale to suit their own purposes because other people have to be persuaded that their assessment is fair.]
Now discuss who might be allowed to make changes such as these and why this scale would not work if anyone could write it how they wanted. [This is an opportunity to introduce the processes scientists use to build consensus around a model such as this scale – e.g., journal articles and conferences where changes are proposed and discussed, the role of professional bodies in arbitrating disputes, etc.]

What’s important here?

Scientists represent their ideas in a variety of ways, including models, graphs, charts, diagrams, written texts – and the measurement scales they use. Students need to understand that scientific scales have been deliberately constructed for specific purposes, and can be refined over time as they are used for these purposes. However, this does not mean that “anything goes” – understanding how critique and consensus building are used to impart authority to such scales is an important aspect of building science literacy. Understanding and using the literacy practices of science supports students to think in new ways.

What are we looking for?

Can students discuss the constructed nature of the Modified Mercalli Intensity scale?

Do they appreciate that the scale descriptors have been developed over time by the consensus-building processes that also apply to science claims more generally?

Opportunities to learn at different curriculum levels

For suggestions about adapting tasks in ways that allow students to show progress in gathering and interpreting data see Progressions .

Exploring further

If students are interested in the actual development of the Mercalli scale over time, a very short history of its development can be found in the Wikipedia:

Mercalli intensity scale .

Other similar scales include the Beaufort scale for wind speed, which is briefly outlined at:

Weather Online: Beaufort Scale

The Science Learning Hub also has an activity in which students study damage descriptions from earthquakes and allocate a Modified Mercalli Intensity (MMI) number:

Student Activity: Earthquake intensity