This tool: IXL is used in more than 150 countries to motivate students and turn maths learning into an engaging experience. The tool gamificates the whole math learning process by introducing videogame-like dynamics, and allowing students to earn prizes and badges when mastering certain skills.
The tool also gives the teachers options to monitorize and record the performance of the stundents and receive their feedback.
The service is not free, but it offers a 30-day free trial. So if you are interested You can try it!