Research has found that successful game-based learning (GBL) is dependent on several factors, e.g. students, parents, teachers and educational setting. Nevertheless, many existing GBL solutions primarily consider the student. Similarly, they focus on imparting and assessing content-specific knowledge rather than encouraging students to become intrinsically motivated learners. This paper presents CURIO, an educational game kit that involves teachers as game masters'. It encourages inquisitive mindsets in students and helps to structure discussions when introducing a new topic in class. It informs the teacher of students' pre-existing knowledge so that they can better shape upcoming classes to their needs. A pilot study with a class of 25 primary school students and their homeroom teacher evaluated a prototype of CURIO. The paper concludes with guidelines learned from creating and testing CURIO that can help with the development of tools for teachers using the same design philosophy.