This Instructional Activity is a part of the Lesson 5, Unit 6, Grade 6. In Lesson 4, we investigated the head circumferences that the boys' and girls' basketball teams collected. Below is the frequency table of the head circumferences that they measured. Isabel, one of the basketball players, indicated that most of the caps were small (S), medium (M), or large (L). To decide if Isabel was correct, the players added a relative frequency column to the table. Relative frequency is the frequency for an interval divided by the total number of data values.