Many teachers, lecturers and presenters use clickers and student response systems to add a level of real-time interaction during a lecture or presentation. Moodle has a inbuilt poll activity called choice which can be set up to allow students select one of a number of options. With so many students having their own mobile devices, this facilitates the teacher to have the students take the choice activity either using the mobile web interface of Moodle, or using the Moodle Mobile App to provide this interaction.
The linked guide takes you through setting up a Moodle web service to view live choice results in a real time dynamic graph - so replacing the clicker requirement and using the students' own mobile devices instead.
See here for the guide: Choice Results