The aim of this research was to describe the implementation of assessment for learning, student activities during learning activities, improving learning outcomes of chemical equilibrium material, and student responses to assessment for learning. The subjects of this study were students of class XI MIPA 4 at SMAN 3 Surabaya. This study uses a pre-experimental research design using One Group Pretest-Posttest Design. The results of this study show that (1) the quality of the implementation of assessment for learning got very good criteria in three meetings with an average percentage of 91.08%, 95.16%, and 95.76%, respectively;(2) During learning, the relevant student activities have a more significant percentage than the irrelevant student activities, which is 93.47% at the first meeting, 94.34% at the second meeting, and 94.44% at the second meeting; (3) The learning outcomes of students have achieved classical completeness of 90.91% and have increased with the percentage of students who obtained the N-gain on the high criteria of 87.88%, while the percentage who obtained the N-gain on the medium criteria is 12.12%; (4) The response of students after the assessment for learning was implemented got a positive response percentage of 90.12% with very good criteria.