Smartphones are increasingly used in schools to achieve a number of educational outcomes; from developing measurement skills to enabling collaborative learning. When used as a measurement device in science classrooms, a few questions emerge. How good are the measurement capabilities of smartphones? Can smartphones lead to a more positive learning experience? What are students' and teachers' attitudes to investigations when smartphones are used to take measurements? This study investigated the use of smartphones as measurement devices in a classroom hands-on investigation to probe the complex phenomenon of light intensity. The investigation was implemented in nine workshops with a total of 93 students and 118 teachers. We report on the design and evaluation of the investigation using a survey consisting of Likert-style questions, measures of mental effort and open-ended responses. Results show that the design features were critical to the success of the investigation and participants found the investigation to be interesting and a valuable learning experience.