The term of one-page lesson plan was used to describe the simplification of the 2013 curriculum with the principles of efficient, effective, and student-oriented. There are three aims in this study. The first aim is to explain how teachers designed the one-page lesson plans. The second one is to describe how the lesson plans’ implemented in the teaching-learning process. The third one is to analyze the obstacles that teachers face when implementing the lesson plan. The participants of this research are three English teachers who teach in grades 7, 8, and 9 at MTs Yapika Kebumen, Central Java. This research used descriptive qualitative method and the research design used case study. The researcher collected the data using interviews, document analysis, and observation. The data from these data collection methods were triangulated. Referring to the result of data analysis, it shows that: (1) The English teachers have designed their lesson plans referring to SE number 14 of 2019 appropriately. (2) Based on study’s findings, all of participants have been quite successful in implementing one-page lesson plan in teaching learning process. The teachers have improvised better than they have planned. The teachers stated that using one-page lesson plans for English subject can shorten their time to prepare lesson plans, so teachers can allocate more time for doing reflection. The teachers also found it easier administratively. (3) The teachers faced some problems in designing one-page lesson plan include: simplifying sentences, determining the objectives at each meeting, and also determining time allocation. The teacher who has less teaching experience faced the problem of internalizing some points that the teacher has planned in teaching-learning process when using One-page lesson plan because of its simplicity.