Through prior IES-funded SBIR projects in 2015 and 2016, the developer created a suite of personalized mathematical learning games and puzzle-based apps. The research team will develop a new prototype component of the apps to assess student progress toward mastery of proportional reasoning. The prototype will include new content to engage students in math thinking and problem-solving behaviors that align with proportional reasoning, a logfile database and algorithm that automatically classifies math thinking and assesses student progress to mastery. At the end of Phase I, in a pilot study with 400 students in grades five and six, the researchers will examine whether the prototype functions as planned, if students are engaged during gameplay, if the prototype adjusts as individual students engage in the activities, and if the prototype's assessment accurately measures student progress toward mastery.