Activity: From Raw Data to Double Graphs
In this activity we'll take raw data and turn it into:
- a double bar graph
- a double line graph
This helps us compare two related sets of data clearly.
What's Raw Data?
Raw data is data that has not yet been organized into a table or graph.
It is often collected by:
- measuring
- counting
- surveying
Before we can draw graphs, we must organize the data first.
Activity 1: Double Bar Graph
A double bar graph is useful when we want to compare two groups across the same categories.
Raw Data
The table shows the number of books read by students in two classes during one term.
| Student | Class A | Class B |
|---|---|---|
| 1 | 4 | 6 |
| 2 | 7 | 5 |
| 3 | 6 | 8 |
| 4 | 5 | 7 |
| 5 | 8 | 6 |
Step 1: Organize the Data
We'll compare the total number of books read in each class.
Add the values for each class:
- Class A total = ______
- Class B total = ______
Step 2: Draw the Double Bar Graph
- Draw a horizontal axis (x-axis) labeled Class
- Draw a vertical axis (y-axis) labeled Number of Books
- Choose a suitable scale (for example, 0 to 40)
- For each class, draw two bars side-by-side
- Use different colors or shading for Class A and Class B
- Add a key (legend) to show which bar is which
Questions
- Which class read more books in total?
- How much greater is the total?
Activity 2: Double Line Graph
A double line graph is useful when we want to compare changes over time.
Raw Data
The table shows the daily temperature recorded in two cities over one week.
| Day | City A (°C) | City B (°C) |
|---|---|---|
| Mon | 18 | 22 |
| Tue | 19 | 21 |
| Wed | 20 | 23 |
| Thu | 22 | 24 |
| Fri | 21 | 22 |
Step 1: Set Up the Axes
- x-axis: Day
- y-axis: Temperature (°C)
Choose a scale that fits all the values.
Step 2: Plot the Data
- Plot the temperatures for City A
- Join the points with straight lines
- Plot the temperatures for City B on the same graph
- Use a different color or line style
- Add a key (legend)
Questions
- On which day was the temperature difference the greatest?
- Which city had the higher temperature most often?
Challenge
Collect your own raw data.
Ideas:
- Daily step count for two people
- Rainfall in two cities over a week
- Scores of two teams across several games
Create:
- one double bar graph
- one double line graph
Explain why each type of graph was suitable.