Several studies have attempted to answer, "How and to what extent are games used in the classroom?" In one study, fifty-three Swedish ESL teachers were surveyed; the outcome determined was that video games in the classroom were barely utilized. Although the teachers were open to the idea, they did not identify the benefits of applying video games to the curriculum. Video games created excitement, not for learning, but for the games. While there are people who do not agree with the idea of using video games in the classroom, others are open- minded to the experiment. Video games are an interactive entertainment. They promote intellectual skills that support academic achievement. In supplying students with educational subject matter, they demonstrated further advantage. Making use of video games in the classroom is simply another technique to engage with students. A study was conducted in a "3 week intervention with game- based learning activities in eight lower secondary classrooms." The study found that video games are a motivation to the students who do not find educational settings interesting. The purpose of the study was to increase engagement and participation of students. Class participation increases retention of the material. Encouragement for student involvement in the classroom is distinctly recommended. Some teachers have attempted to use video games within a classroom setting. There is some evidence which shows that for young children, educational video games promote student engagement. Video games are inherently incentive-based systems with the player being rewarded for solving a problem or completing a mission, while meeting certain criteria. As a result, video games train a systematic way of thinking as well as an understanding for how different variables affect each other. Furthermore, video games can constantly and automatically assess the learner's ability at any given moment due to the software-based nature of the medium; modular education structures tend to deliver assessments in large chunks and present a relatively limited picture of student progress. Video games such as "Minecraft" and "Portal" have been suggested as platforms for teachers to experiment with their educational abilities. "Minecraft" is a sandbox game in which the user can create objects using the crafting system, while "Portal" is a physics game: the player uses the laws of physics, such as gravity and inertia, to advance through the game's series of test chambers. Critical thinking and problem solving are inherent in the latter game's design. Both "Minecraft" and "Portal" are adaptable to some learning environments; for instance, "Minecraft" has been used for young children while "Portal" has been used by high school physics teachers. "Portal 2" has also been used to develop cognitive skills in older undergraduate students, however.