 Teacher resources and professional development across the curriculum

Teacher professional development and classroom resources across the curriculum            Session 3, Part A:
Organizing Data in a Stem and Leaf Plot

In This Part:
How Long Is a Minute? | Making a Stem and Leaf Plot | Ordering a Stem and Leaf Plot
Interpreting the Stem and Leaf Plot | Grouping by Fives | Ordering Low and High

The stem and leaf plot for the 26 estimates of elapsed time illustrates a grouping of the data by tens; for example, the first stem contains all values from 30 to 39. A stem and leaf plot, however, does not have to group the data by tens -- we could have grouped by fives, for instance. If we were grouping by fives, we would consider all possible numbers in the 50s, for instance, and then put them in two groups, the High and the Low:

 Low Group High Group 50 51 52 53 54 55 56 57 58 59

When forming the stems for a grouping by fives, we consider the second digit of each number as well as the first:

 • Numbers in the Low Group end with a second digit of 0, 1, 2, 3, or 4. • Numbers in the High Group end with a second digit of 5, 6, 7, 8, or 9.

Note that the two groups each have the same number of possible second digits (5). When creating a stem and leaf plot, all stems should have the same number of possible leaves.

To classify our 26 responses in this way, we set up our stem and leaf plot with stems corresponding to the Highs (H) and Lows (L) and then group the responses accordingly. For example, the first data value (63) is on stem 6L since its leaf, 3, is in the Low Group:  26 Responses to the Question   63 67 79 75 57 72 52 89 39 59 55 68 66 86 70 52 60 64 42 54 56 82 57 65 59 33      Problem A7 Use the Interactive Activity below to convert the stem and leaf plot grouped by tens into a stem and leaf plot grouped by fives (or regroup them on paper).    Session 3: Index | Notes | Solutions | Video