In this lesson, students continue to choose appropriate representation (MP5) to display categorical and numerical data, reason abstractly and quantitatively (MP2) by interpreting the displays in context, and study and comment on features of data distributions they show. Here they begin to use the everyday meaning of the word “typical” to describe a characteristic of a group. They are also introduced to the idea of using center and spread to describe distributions generally. Planted here are seeds for the idea that values near the center of the distribution can be considered “typical” in some sense. These concepts are explored informally at this stage but will be formalized over time, as students gain more experience in describing distributions and more exposure to different kinds of distributions.
- Describe (orally and in writing) a distribution represented by a dot plot, including informal observations about its center and spread.
- Interpret a dot plot to answer (in writing) statistical questions about a data set and to identify (orally) what values are “typical” for the distribution.
Let's investigate what dot plots and bar graphs can tell us.
- I can describe the center and spread of data from a dot plot.
The distribution tells how many times each value occurs in a data set. For example, in the data set blue, blue, green, blue, orange, the distribution is 3 blues, 1 green, and 1 orange.
Here is a dot plot that shows the distribution for the data set 6, 10, 7, 35, 7, 36, 32, 10, 7, 35.
The frequency of a data value is how many times it occurs in the data set.
For example, there were 20 dogs in a park. The table shows the frequency of each color.
color frequency white 4 brown 7 black 3 multi-color 6