A good graph makes the intended comparison clear. Start with the question, not your favourite chart style.
Choose a representation that suits the data, the context and the question being investigated.
A bar graph compares amounts in categories. A double bar graph compares the same categories across two groups using a shared scale. A line graph shows change across an ordered numerical variable, often time. A circle graph shows non-overlapping parts of one whole. These are choices for communicating a relationship, not rules based only on how the graph looks.
For measurements at equally spaced times, equally spaced positions on the horizontal axis are appropriate. If observations occur on days 1, 2 and 10, placing all three points at equal distances hides the long gap. A connecting line suggests a progression between observations; it does not prove that the intermediate values were measured.
Circle graphs work when every part belongs to the same total and categories do not overlap. If students can select several favourite sports, category percentages may sum to more than 100%. A circle graph would falsely imply one partition of a whole; a bar graph can show the number choosing each option. Always state whether percentages refer to respondents or total selections.
The same weekly sales data can be displayed as bars to compare individual days or as a line to emphasise change over time. Justify the choice using the question. ‘It looks nice’ is a preference; ‘it makes the Tuesday-to-Friday change easy to follow’ is a mathematical reason.
Enter one label and value per line, separated by a comma. This tool supports 2–12 non-negative values. The table and graph always use the same data.
Line graphs use equally spaced positions here: use observations at equal time intervals. Do not use a line to connect unrelated categories. Circle graphs require a positive total.
The same grade categories occur in two groups.
A double bar graph places each pair beside one another on the same scale. Include a legend, grade labels and units. Keep the groups’ definitions and counting periods consistent.
What would the whole represent?
Adding temperatures does not form a meaningful whole to partition. Use a line graph for a time pattern or bars for individual-day comparisons.
Feedback explains your chosen response. These activities are practice, not a school mark.
Use the original Graphing Tasks package: compare the gaming teams, follow the homeroom step patterns and investigate lunch preferences. Select a graph because it answers the task’s question.
Display one dataset as both bars and a circle graph. Write one question each representation answers especially well, and one detail that is harder to judge.