The goal of this study is to improve high school chemistry teacher's competency in terms of classroom instruction. This goal is achieved through the workshop and continuous assistance activities that enable teachers to improve their knowledge and skills in developing learning scenarios that reflect scientific methods (brain-based learning) in the classroom instruction. The effect of teachers' competence improvement was measured by a survey of student's perception on the classroom teaching-learning process, using Likert-scale questionnaire. The first poll was conducted before the program was started, and the second one was after the program completion. The first observation shows that only 18% of students perceive that the chemistry learning process in the classroom are “good,” while the rest (82%) say that it is “fair”. However, the second poll shows that there are 45% of students who perceive that the learning process is “good”; interestingly, there are 35%, and 20% of respondents say “excellent” and “fair,” respectively. Furthermore, data analyses using chi-square test conclude that the continuous teacher assistance activity significantly improves teachers' competencies. This article describes detailed of collaboration program and the results of improvement of chemistry teachers' competence in north Lombok regency.