2.1 Block diagrams

A block diagram is a version of a bar chart which uses equal size blocks to represent information. You have already seen an example of these earlier in the course when we looked at picturing the mean; a similar diagram is included again below.

Figure 6 Block diagram to represent pocket money of three siblings

From this diagram, we can see that Aisla has £4, Tom has £10 and Gio has £6 in pocket money. Notice the similarity between this diagram and pictograms as discussed in the previous section. Block diagrams can be a useful stepping stone between pictograms and bar charts to aid development of learner understanding.

Block diagrams come in various formats, you will see another example in the next activity.

The important aspects to note are below:

• The blocks should all be equal in shape and size;

• If the diagram is representing discrete data, for instance frequencies allocated to separate categories, there should be gaps between the row or column of blocks representing each category.

Draw a block diagram to represent the data in this frequency table.

Table 1 Daily attendance at Chess Club

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Remember to consider how much each block will represent.

Comment

Your diagram will depend on the value you have chosen for each block. All the frequencies are multiples of 1, 2 and 4 so any of these will work. The following diagram uses a frequency scale rather than a key and each block represents 4 attendees. When presented in this way, the similarity to a bar chart becomes clear.

Figure 7 Example block diagram for daily attendance at chess club

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