Services like Super Maths World allow students to play games to help them to learn about subject areas.  These engage students but teach them at the same time.

Super Maths World

BBC Bitesize
 
(Note you cannot 'create games' yet on a mobile device but students can play the games and you can view statistics)
This is one of the few tools placed on this website which is not free. It is included because it is well worth considering purchasing if you do not already have it. 

I am Learning is a great tool to help you create online games for your students to play.  These games can be used to engage students with a topic as well as to test their understanding of it.

The student plays a game which includes questions previously set up by the teacher.  The better they perform at the questions, they easier it is to play the game and achieve a high score.  Students can keep trying to better their score and can choose from a wide variety of different games to play.

As a teacher you get to see a wide range of statistics which help you to identify and address areas of underperformance in a cohort, class or for an individual.

To find out more about I am Learning click here: http://www.iamlearning.co.uk/

For a video overview please see below: