1. 3-3 6th grade math
Stem-and-Leaf Plots

2. Objective
To use stem-and-leaf plots to analyze central tendencies of data with 2 or 3 digit numbers.
Why? To know another way to analyze data. It is a quick way to show numeric data and study its distribution.

3. California State Standards
MR 2.4: Use a variety of methods, such as … graphs, tables, … and models, to explain mathematical reasoning. SDP 1.2: Understand how additional data added to data sets may affect these computations of measures of central tendency. SDP 1.4: Know why a specific measure of central tendency (mean, median, mode) provides the most useful information in a given context.

4. How to Set Up a Stem-and-Leaf Plot Graph to 2 Digit Data
56, 70, 98, 92, 72, 85, 80, 85, 89, 81, 104, 96:
List the tens digits in a column from the least to greatest. STEM
Next draw a vertical line to the right of this column.
LEAVES: Then for each number in the set, the ones digit is placed after the appropriate tens digit. These digits are listed from least to greatest and are repeated for duplicate numbers occurring in the set. It should resemble a bar graph.
Title the Graph
56, 70, 98, 92, 72, 85, 80, 85, 89, 81, 104, 96:
Stem
Leaves 5 6 7
0, 2 8
0, 1, 5, 5, 9 9
2, 6, 8 10 4

5. How to Find Median Using Stem-and-Leaf Plots
The median can be found by counting from either end of the plot until the center is found. If there are an even number of data values, the two center numbers are averaged.
85 = median
Stem
Leaves 5 6 7
0, 2 8
0, 1, 5, 5, 9 9
2, 6, 8 10 4

6. How to Find Mode Using Stem-and-Leaf Plots
Leaves 5 6 7
0, 2 8
0, 1, 5, 5, 9 9
2, 6, 8 10 4
The mode is easily determined by noting which number occurs most often.

7. How to Find Mean Using Stem-and-Leaf Plots
You will still need to find the average of all the numbers in the set. Add to find its total and then divide by the quantity in the set.
Total = 1008 ÷ 12 = 84
Stem
Leaves 5 6 7
0, 2 8
0, 1, 5, 5, 9 9
2, 6, 8 10 4

8. How to Find Range Using Stem-and-Leaf Plots
104 – 56 = 48 Range = 48 numbers in the data set
Stem
Leaves 5 6 7
0, 2 8
0, 1, 5, 5, 9 9
2, 6, 8 10 4
Use the same rules to find the range. Subtract the least number in the set from the greatest number.

9. Putting all the information together.
Median = 85
Mode = 85
Mean = 84
Statistically: the data is relevant.

10. Try It! Use the Stem-and-Leaf Plot to find Range = 46 – 7 = 39
Median = 33
Mode = none
Stem
Leaves 7 1
4, 8 2
3, 8 3
3, 5 4
0, 2, 5, 6
Use the Stem-and-Leaf Plot to find
The range
The median
The mode

11. Objective Review
To use stem-and-leaf plots to analyze central tendencies of data with 2 or 3 digit numbers.
Why? You now know another way to analyze data. It is a quick way to show numeric data and study its distribution.

12. Independent Practice Complete problems 5-10 Follow all directions
Show all work!
If time, complete Mixed Review: 11-14
If still more time, work on Accelerated Math.