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SingaporeComputer ScienceSyllabus dot point

How do we turn rows of data into a clear chart, and find the rows we want?

Choose an appropriate chart type for data, and use sorting and filtering to organise and find records

A focused answer to the O-Level Computing point on presenting data. Choosing a suitable chart (bar, line, pie), sorting records into order, and filtering to show only the rows that meet a condition.

Generated by Claude Opus 4.86 min answer

Reviewed by: AI editorial process; not yet individually human-reviewed

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  1. What this dot point is asking
  2. The answer
  3. Examples in context
  4. Try this

What this dot point is asking

SEAB wants you to choose a chart that suits the data, and to use sorting and filtering to organise records and find the ones you want. The central idea is that a chart makes patterns visible, sorting puts rows in a useful order, and filtering hides the rows that do not match a condition so only the relevant records remain.

The answer

Choosing a chart type

Different charts suit different jobs:

Chart Best for
Bar (or column) chart comparing separate categories (sales by product)
Line chart showing a trend over time (temperature each day)
Pie chart showing parts of a whole (each subject's share of study time)

A good chart needs clear axis labels, a title and, where helpful, a legend, so the reader understands it without the original table.

Sorting

Sorting rearranges the rows of a table into order based on one column. You can sort:

  • Ascending: smallest to largest, or A to Z.
  • Descending: largest to smallest, or Z to A.

Crucially, the whole row moves together, so a name stays with its mark. Sorting changes the order of records but not their contents.

Filtering

Filtering temporarily hides the rows that do not meet a condition, leaving only the matching records visible. The data is not deleted or reordered; clearing the filter brings every row back.

A filter can use one condition (Mark greater than 8080) or several combined with AND or OR (Class is 'S3A' AND Mark greater than 8080).

Sorting versus filtering

The key difference: sorting reorders all the rows; filtering shows only a subset. They are often used together, for example filter to the rows you care about, then sort those into order.

Examples in context

Example 1. A weather log. A student records the daily maximum temperature for a month and draws a line chart. The line makes the warming or cooling trend obvious, which a table of numbers alone would not, helping spot the hottest week at a glance.

Example 2. A library catalogue. A librarian filters a book list to show only titles borrowed this year, then sorts the result by author. Filtering removes the irrelevant rows and sorting puts the remaining books in a useful order for shelving.

Try this

Q1. State the most suitable chart to show how a class's study time is divided between subjects. [2 marks]

  • Cue. A pie chart, because it shows each subject as a slice of the whole.

Q2. Explain what happens to a table when it is sorted by a column in ascending order. [2 marks]

  • Cue. The rows are rearranged smallest to largest (or A to Z) on that column, with each whole row kept together.

Q3. State the difference between sorting and filtering a table. [2 marks]

  • Cue. Sorting reorders all the rows; filtering hides the rows that do not meet a condition, showing only the matches.

Exam-style practice questions

Practice questions written in the style of SEAB exam questions on this dot point, with worked answer explainers. The year tag is the paper they imitate, not the source.

Original4 marksA shop has sales figures for each month of one year. (a) State the most suitable chart type to show how sales changed over the year, and give a reason. (b) State a more suitable chart type if instead you wanted to show each product's share of total sales.
Show worked answer →

(a) A line chart is most suitable for sales over the year, because a line shows a trend over time clearly: the audience can see at a glance whether sales rose, fell or stayed steady from month to month.

(b) A pie chart is more suitable for showing each product's share of the total, because a pie shows parts of a whole as slices, making proportions easy to compare.

Markers reward a line chart for a trend over time with a reason, and a pie chart for proportions of a whole.

Original5 marksA table lists students with columns for Name, Class and Mark. (a) Explain what sorting the table by Mark in descending order would do. (b) Explain how filtering differs from sorting. (c) Describe a filter that would show only students in class 'S3A' who scored above 8080.
Show worked answer →

(a) Sorting by Mark in descending order rearranges all the rows so the highest mark is at the top and the lowest at the bottom. Every row stays intact (the name stays with its mark); only the order changes.

(b) Filtering does not reorder the data; it temporarily hides rows that do not meet a condition, showing only the matching records. Sorting reorders all rows; filtering shows a subset.

(c) Apply two conditions: Class equal to 'S3A' AND Mark greater than 8080. Only rows meeting both are shown; all others are hidden until the filter is cleared.

Markers reward sorting reordering whole rows by Mark, filtering hiding non-matching rows rather than reordering, and a correct two-condition filter.

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