Algebra I : Unit #5 - Modeling With Statistics : Lesson #4

Organizing Data with a Box Plot

Objective: SWBAT construct a box plot and understand how a box plot represents the distribution of data in a data set.
Standards: HSS-ID.A.1 HSS-ID.A.2 HSS-ID.A.3 MP1 MP2 MP3 MP6
Subject(s): Math
45 minutes
1 Opening - 10 minutes
2 Direct Instruction - 10 minutes

When teaching this topic, I like to front load the vocabulary of working with a box plot.  In Slide 4 of Box Plot_Day 1, I expose students to the terms that are used when working with box plots. When discussing the vocabulary, I work horizontally across the boxes so that students can see a connection between the words used and the plot.

I continually refer back to the beginning of the lesson when students divided data into four equal parts so the term "quartile" (quarter) makes sense to them.  Going across the rows the terms would be:

1st quartile....2nd quartile...3rd quartile

lower quartile...median...upper quartile

25th percentile...50th percentile...75th percentile

3 Investigation - 15 minutes

On the front side of Stats_Box_Plot_Introduction, I want my students to connect the idea of dividing a data set into quarters with finding multiples of 25% of a number.  This portion of the lesson does require students to understand and think through what they are trying to find (MP1). Hopefully, students will make the connection to the term "percentile" from the vocabulary portion of the lesson.  They will begin to understand how the test scores are distributed when they answer Questions 4, 5, and 6.  

On the back side of the worksheet, students put the data points in order and divide the data into four equal portions.  As a group, we name each of the three divisions they have found using the vocabulary from earlier in the lesson and then construct a box plot on the graph at the bottom of the paper.  As a class, we have a discussion about how the same number of scores (4) are in each of the sections of the box plot (MP7).

4 Closure - 5 minutes

The question on Slide 5 of Box_Plot_Day 1 requires students to apply what they have just learned to a more abstract scenario when the data points are not given.  I usually give students a couple of minutes to think about what the vocabulary from the question means and allow them to make a sketch of how to visualize the problem.  Then I ask them to compare their idea with their partner's and come up with a common answer.