This study is based on implementing backward design to improve students’ academic assessment, so public high school students can take part of meaningful contexts where they show what they learned at the end of a class term. Taking in consideration, backward design is a great tool to be applied for public high schools where most of the classes are textbooks centered, provoking students’ frustration due to the lack of English knowledge from schools. There is a high rate of students failing courses because students are placed in English levels where they do not belong to or they come from other institutions where they did not learn English. Backward design lets teachers be creative and use skills and methodologies according to students’ needs and be very reflexive in the way of designing it. In this study, pairedT_Test is applied to compare scores from the same level, but using different ways of testing. In conclusion, the experimental group (G2), in which backward design was applied, got better results than the controlled group (G1), who did not apply it. In this case the independent variable which mean and scores are high. Results show backward design is very meaningful not only for students, but also for teachers. It is true that running appropriate action plans, selecting the best resources and conducting a final assessment through a performance task, gave the opportunity for students to gain more confidence on the language and apply it in a real context.