The flipped classroom technique helps learners to become active rather than passive receptacles of information (jinlei, ying & baohui, 2012) finding the opportunity to build their own knowledge at their own pace. Based on this principle, the researchers wanted to compare the impact and effectiveness of the flipped classroom technique on efl students’ achievement versus a traditional classroom instruction to teach grammar. This study was designed to gather evidence from 2 groups of 40 students each who were taking the intermediate course (b1) in a public university in guayaquil, ecuador to determine if they performed better in the flipped classroom or in the traditional classroom. For the flipped classroom, the teacher looked for videos to learn grammar together with some powerpoint presentations to be seen and checked at home. Students then got ready for the next session. Students returned to their classrooms.