This document outlines a lesson plan for teaching measures of position for ungrouped data in Grade 10 Mathematics. The lesson focuses on calculating quartiles. Students will illustrate and calculate the quartiles in ungrouped data sets. They will practice finding the first quartile (Q1), second quartile (Q2/median), and third quartile (Q3) using formulas and examples. The lesson motivates students with a data set example of customer numbers at a coffee shop and has them find Q1 and Q3. Formulas for Q1 and Q3 using the Mendenhall and Sincich method are provided. Students will complete an activity finding quartiles in sample data sets in pairs.