In Thailand, the traditional teaching approach used for English language classes has been to explicitly teach English grammar, but in recent years the strategy has begun to shift towards the implicit teaching of language via communicative techniques. Within academic circles, there has been minimal agreement on the suitability of approaches used. Today, the question of whether it is better to use an implicit or explicit approach remains open to debate. In this study, an explicit approach is used to teach English grammar to learners in the English Program at the Faculty of Education, Lampang Rajabhat University. These learners have experienced implicit teaching during their own learning of English grammar, but upon graduation will have to use explicit methods when they become teachers of English grammar themselves. Initially, it can be observed that their knowledge of English grammar is weak. Also, they may lack the pedagogical skills to teach English grammar explicitly. The target group in this study was 74 Year 1 students. This study involved multiple steps, namely content analysis, a pre-test, explicit English grammar tutoring, a post-test and data analysis. Test results were statistically analysed for percentages, means and standard deviations. Pre- and post-test scores revealed a difference of 360, or 12.16%, with the mean of 4.87 (SD = 9.96). It can be seen that English grammar learning skills of the target group can be developed by using the explicit teaching method and this can support pre-service English teachers to teach grammar more effectively.