Percentiles & Cumulative Relative Frequency Graphs
Chapter 2  Day 1  Lesson 2.1
Learning Targets

Find and interpret the percentile of an individual value in a distribution of data.

Estimate percentiles and individual values using a cumulative relative frequency graph.
Activity: Where Do I Stand? Part 2
In lesson 1.3, we collected data about the students’ heights. Today we will use a sample of 20 of those students to explore percentiles and cumulative relative frequencies. Revisiting contexts from earlier lessons is a great way to build continuity and connections. You’ll notice throughout the year that we will often use one scenario for many different lessons. Before you teach this lesson, take a random sample of 20 students and enter their heights into stapplet.com. Copy the dotplot and the summary statistics into the activity page.
Students will be able to work through #13 on the activity page in groups without any teacher input. Debrief with the group after #3, pointing out where students calculated percentiles. Then have the groups continue working to finish the page. They may have questions about what a cumulative relative frequency graph should look like, but other than that, they had no issues when we went through this lesson. This activity is a great example of how students should experience first, and formalize later. You’ll see on the answer key that anything written in black is what we expect the students to work through in groups without much teacher input. This is how students experience statistics. We have students write their work on the white board for us to go over. At that time, we add in formal language and content in the margins of the page. This is how we formalize the learning. We wrote this is red on the activity page key. You should make sure that students are aware that you are doing this so they know to pay special attention to what is in the margins.
Check Your Understanding
After the group work, we’ll complete the Big Ideas section. This is usually the only direct instruction we give during a lesson. We always make sure to bring this portion back to the learning targets. This helps us to stay focused on exactly what students need to master. Students should then work with their groups again to complete the Check Your Understanding problems. You could circulate around the room and check each group or have students write their work on the board.