This study reports on a classroom activity for Grade 5 students investigating their reaction times. The investigation was part of a 3-year research project introducing students to informal inference and giving them experience carrying out the practice of statistics. For this activity the focus within the practice of statistics was on introducing two different ways of collecting data to answer a statistical question, in this case, "What is the typical reaction time of Grade 5 students?" Workbook entries were used to assess students' capacities to engage in the investigation. Results indicated that although the students were proficient with the procedures and measures introduced, they were less able to explain and apply the underlying concepts. The activity provides a suggestion and benchmarks for others wishing to follow student development of concepts related to the practice of statistics.