1. Columns are equally spaced apart.
2. Columns may be vertical or horizontal.
3. The graph starts half of one column width into the horizontal axis.
4. Each column has the same width.
5. Label both the vertical and horizontal axes.
6. Place the appropriate scale on both axes.
7. Label the graph with an appropriate title.

A sector graph is a data display that uses a circle divided proportionally into sectors to represent the parts of a total.

1. Use a compass to draw a circle.
2. Draw a radius – a line from the centre of the circle to the circumference as a reference line for measuring and creating each sector.
3. Determine the size of each sector. If the size is given as a percentage, multiply the percentage by 360 this will give the required angle of each sector which can be measured with a protractor on the radius line.
   For example:
   A sector representing 50%, ⁵⁰⁄₁₀₀ x 360 = 180°
   A sector representing 25%, ²⁵⁄₁₀₀ x 360 = 90°
   A sector representing 10%, ¹⁰⁄₁₀₀ x 360 = 36°
   If the size is given as a number out of a total number, convert to a fraction and multiply by 360 to get the angle of each sector.
   For example:
   A sector representing 4 out of 20, ⁴⁄₂₀ x 360 = 72°
   A sector representing 6 out of 20, ⁶⁄₂₀ x 360 = 108°
   A sector representing 10 out of 20, ¹⁰⁄₂₀ x 360 = 180°
4. To ensure you have not made a mistake check that all the sectors add to 360.
5. Use a different colour to represent each sector, label each sector or create a key to represent each sector.
6. Place a title at the top of the sector graph.

Divided bar graphs are used to show how a total is divided into parts. A divided bar graph uses a single bar divided proportionally into sections to represent the parts of a total.

• The proportion of the rectangle indicates the part of the ‘whole’ that each graphed amount represents.
• It is important to know the exact size of the whole, as each section of the bar represents a fraction of that amount.

1. Draw a rectangle and divide accordingly. The length of each section should represent the percentages shown e.g. the orange bar should be 60% of the length of the rectangle.
2. Label each section and include the percentage.
3. Place an appropriate title for the divided bar graph.

A Dot plot displays scores which are indicated by symbols such as dots drawn above a horizontal axis.

Each piece of data is represented by a single dot.

Dot plots can be used as an alternative to a column graph and are usually only for small data collections.

Population Pyramids are graphical illustrations that show the distribution of various age groups in a population.

• They typically consist of two back-to-back graphs.
• The population plotted on the x-axis (horizontal) and age on the y-axis (vertical).
• One graph shows the number of males and one graph shows the number of females in a particular population. The age scale is in five-year age groups and are called cohorts.
• Males are conventionally shown on the left and females on the right.
• Amounts may be measured by raw numbers or as a percentage of the total population.
• Unpack each aspect of the population pyramid with students. Start with each axis and progress students to making general statements and conclusions about the data.

1. Look at the vertical scale on the y-axis. What do the numbers represent?
2. Look at the horizontal scale on the x-axis. What do the numbers represent? Are they in whole numbers or percentages?
3. Look at the left hand side graph. What data is shown?
4. Look at the right hand side graph. What data is shown?
5. What does each column represent? Look at the size of the columns and the overall formation of the pyramid. What does the shape show?
6. What is your age groups’ population?
7. What can you say about the aging population?