The application - "Socrative" empowers teachers to engage and assess students as learning happens. Teachers can use of real-time questioning, result aggregation (in real time and in reports), and visualization. The best feature is that teachers have instant insight into levels of understanding so that class time can more efficiently be used to work with a variety of student abilities.
https://goo.gl/Bv6zDQ Socrative for teacher and student on the IPAD.