There are many mobile applications that can be used in the classroom to motivate students and test their learning: Memrise, Kahoot!... But in the courses of the younger students (12-13 years old) we have a problem with the smartphones: they aren’t allowed in the classroom, and some students do not even have it.
There is an app very similar to Kahoot! that allows you to do tests in the classroom without this problem, since it works through BIDI codes assigned to each student. Then you can project a test on the board, the students choose between the 3 or 4 available options and show their BIDI code oriented according to the chosen answer; through the mobile phone the teacher captures the students' answers and these are immediately projected on the board.