1.1 Appropriate symbols

The symbol of a person in the previous example seems appropriate until we consider the final point; what if a fraction of a symbol is needed? You might consider how accurate the representation needs to be, i.e. is the exact value represented by a part of a symbol important in what you are trying to display?

Activity 3

Timing: Allow 5 minutes

Below is a pictogram representing how school children from a small town travelled to school in 2022. This data is collected by the UK government.

Write down if you think this is a good or bad example of a pictogram. Give reasons to support your thoughts.

Figure 3 Mode of travel pictogram

Add image here

Comment

Although it looks pleasing to have different symbols to represent each mode of transport, this is not good mathematical practice. Due to the different shapes and sizes of the images it can be difficult for the brain to visually interpret that each symbol represents the same value.

One issue you may have identified is it appears visually that the number of pupils who walk is a little less than the number who catch the local bus since the total length of the symbols for each of these is very similar. However, using the key, more than double the number of children walk than catch the local bus.

It would be much better to choose one symbol to use to represent all modes of transport.

Otherwise, the pictogram is well set out and labelled clearly with a key included.

The source of the data should also be included.

Learners like to customise their pictograms either by using different symbols for different data items, as in Activity 3, or using different colours for different data items. They sometimes like to use complex images as their chosen symbol, and this can present difficulties when interpreting fractions of a symbol.

The goal is to keep it simple with a symbol that is easy to interpret. When using fractions of a symbol it should be clear as to whether the length, or the area, of the symbol is important.

In Figure 4, the original symbol appears the same when halved either by length or by area but when you compare the middle images representing three-quarters of the overall amount, you will see there is quite a difference. Perhaps you have a preference as to which is better.

Figure 4 Images to represent using length or area of symbol for pictograms

There are ways to deal with this problem including ensuring the symbol used can be easily adapted to clearly represent the frequency values required for the data.

For instance, if we are happy to present all our population data for the UK four nations pictogram to the nearest million, we would only require two versions of the symbol:

Figure 5 Pictogram population key