This paper describes iFractions, a free Game Based Learning tool to teach fractions, its didactical motivation, and its two first tests with users, prospective math teacher, and children. It was designed for children from 6 to 10 years old and it was developed in HTML5, JavaScript, Mysql, and phaser.io framework. It was developed considering the six facets framework to serious game. iFractions was first evaluated by 29 math prospective teachers; all of them enrolled in a non-mandatory undergraduate discipline of the Institute of Mathematics and Statistics of the University of São Paulo (Brazil). For the purpose of the study, 25 videos recorded were analyzed; they have a total duration of 211.76 minutes. On average, they have 8.47 minutes of duration, 17.51 minutes of the maximum duration, and the shortest video last for 1.21 minutes. In conclusion, it has been observed that 76% of users were able to complete three activities without problems. 24% of them completed only one or two activities. After this, the software received some improvement and a group of children tested it.