# 2.1 Getting a sense of scale

In spite of ‘joined up’ planning in schools like Millersneuk Primary, children learn about different science topics in school as distinct blocks of work. One result of this is that the relative sizes of the things they’re learning about are not immediately clear to them. For example, consider how the girls in Figure 4 would know how the ladybirds in their ‘bug hotel’ compare to other objects such as a plant cell or the Earth in terms of scale.

Figure 4 Observing the ‘bug hotel’ in the school bug garden

## Activity 4 Scale

Allow about 10 minutes

Put the following in order of magnitude, from smallest to largest:

## Table 1 Placing objects in size order

ladybird | bacterium | the Earth | flea | galaxy
human being | atom | molecule | plant cell | proton
red blood cell | solar system | star | universe | virus

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### Answer

The objects should be listed in the following order:

(smallest)

- proton
- atom
- molecule

Note: A micrometre (micron) is 1 millionth of a metre (note the English spelling). Protons, atoms and molecules are too small to be measured in this way.

- virus
- bacteria
- red blood cell
- plant cell
- flea
- ladybird
- human being
- the Earth
- star
- solar system
- galaxy
- universe

(largest)

Learning about these things as separate topics means children don’t get a sense of the size of things that cannot be seen by the naked eye, or are so large that size is just a number (a very large one). You can help children to get a sense of scale by including opportunities for them to think across topics, and supporting them to make meaningful comparisons.

OpenLearn - Primary science: supporting children’s learning
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