Lesson Plan - Get It!
Mrs. Thompson's students received the following scores on their recent math test. How can Mrs. Thompson organize the scores so she can easily see how many students fall into each percentile?
97, 62, 97, 97, 88, 83, 94, 97, 83, 75, 88, 75, 94, 83, 94, 75, 97
Looking at the test scores above, there are a few ways Mrs. Thompson could organize the data.
She could insert the data into a table or create a bar graph, but one of the easiest ways she could organize this information is by using a stem-and-leaf plot. A stem-and-leaf plot is a table that lists every piece of data from least to greatest. A stem-and-leaf plot is divided into two obvious sections: the stem and the leaves.
Look at the image below. It shows the test scores from Mrs. Thompson's class organized in a stem-and-leaf plot. Show your teacher or parent where the stem is and where the leaves are. Then, discuss what you notice about the stem-and-leaf plot. Be sure to pay attention to how the numbers are arranged, and how many pieces of data are included:
There are a few things you should have noticed about the stem-and-leaf plot:
- The stem represents the tens place value.
- The numbers that make up the stem are listed from least (top) to greatest (bottom). Even the numbers for which there is no data (10, 20, 30, 40, and 50) are listed.
- The leaves represent the ones place value.
- The numbers that make up the leaves are also listed from least to greatest.
- Every piece of data is represented, even numbers that are repeated. For example, Mrs. Thompson had five students score a 97 on their math test. The 97 is represented in the stem-and-leaf plot five times.
- A comma is used to separate data.
Did you make all of these observations when looking at the data in the stem-and-leaf plot?
Stem-and-leaf plots make it easier for you to read a series of numerical data. Use the stem-and-leaf plot above to help you answer the following questions (the answers are listed at the bottom of the Go! section; no peeking!). Discuss your answers with your teacher or parent:
- How did the majority of students do on the math test?
- In what percentile (60%, 70%, 80%, etc.), did the most students score?
- How many students scored below 70%?
- How many students scored above 80%?
- Did the stem-and-leaf plot make it easier for you to answer these questions? Why or why not?
Surely, you found using the stem-and-leaf plot made answering the questions easier. When you are ready, move on to the Got It? section to practice making your own stem-and-leaf plot.