## Plot It

### Alice BobeBay District Schools

#### Description

Students use a stem-and-leaf plot from a set of data to identify the range, median, and mode of their own math grades.

#### Objectives

The student uses range and measures of central tendency in real-world situations.

#### Materials

-Paper
-Pencil
-Number cube for each student
-Index card for each student containing nine grades of individual student's math scores

#### Preparations

1. Prepare index cards of math grades for each student.
2. Gather number cubes. (dice)
3. Prepare examples of stem-and-leaf plots.
4. Prepare examples of range, mode, and median.

#### Procedures

1. Begin the lesson by reviewing how people organize data in many ways. Tell the students that making a stem-and leaf plot is another way to organize information.

2. In a group setting, give each student a number cube. The student rolls the cube twice and writes this down as a two-digit number. (It makes no difference whether the first toss is used as the tens or the ones digit.)

3. Call on at least eight students to tell their numbers as you record responses on the board.

4. Ask: Is the information on the board organized? Discuss possible answers.

5. Ask: What can be done to organize the data? Discuss possible answers. Examples: Order the numbers from least to greatest or group the numbers by the digit in the tens place.

6. Introduce and discuss stem-and-leaf plot--provides a concise way to organize many numbers by their front digits. Then ask the students to organize the numbers in order from least to greatest. Record the tens digits in order (ex. 20, 30, 40) to the left of a vertical line, and label it Stem. Record each ones digit from least to greatest to the right of the vertical line and label it Leaf.

7. Divide students into small groups of four or more and give them time to practice making stem-and-leaf plots (about 10 minutes).

8. Return to large group setting, review and discuss the new data the students collected while using the cube.

9. Introduce and discuss range, mode, and median. Range is the difference between the greatest and the least numbers. Example: If given nine numbers, subtract one from the total: 9 - l = 8; the range would be 8. Mode is the number that occurs most often in a set of given numbers. Median is the middle number when the number is arranged in order. Example: If given nine numbers, the middle number is the fifth number or numeral 5.

10. Write sample grades in math on the board. Example: 91, 96, 85, 88, 95, 92, 88, 97and 93. Call on a student to construct a stem-and-leaf plot on the board.

11. Draw a diagram on the board to explain the results of the math scores using range, mode, and median. Example: Range =12, Median =91, and Mode =88

12. Share the rubric found in the attached file with the students. Review each element with them and answer any questions that arise.

13. Give each student an index card with nine of his or her math grades. Ask them to arrange the scores in a stem-and-leaf plot and to determine the range, mode and median. Direct them to record their information on paper.

#### Assessments

Assess the final activity using the criteria contained in the rubric (see attached file).

#### Extensions

Students with exceptionalities may have a partner and/or work in a small group.

Students can use stem-and-leaf plot to organize a weather report from temperatures in a newspaper to find the range, mode, and median temperatures.

Teachers can provide a puzzle to acquire the range, mode, and median. Example: The range is 8, the median is 13, and the mode is 12. Fill in the missing numbers in this set of ordered data:

___, 11, 12, ___, ___, 14, 15, 16, 17

#### Attached Files

A rubric with criteria to help with assessment of the lesson.     File Extension: pdf