In synchronous online EFL classrooms, students often exhibit passive participation and boredom when learning grammar. This research study presents the development of an online active grammar learning instructional model, named LPCR, which incorporates Byrne's Presentation-Practice Production (PPP) approach and Fink's holistic view of active learning. LPCR was employed as an eclectic approach for teaching grammar and utilized four online applications in a synchronous online classroom. The study involved 40 second-year nursing students enrolled in an EFL undergraduate course at a public university in Thailand from January to April 2022. The effectiveness of LPCR was assessed through a grammar test, a questionnaire, and semi-structured interviews. The students' grammar scores were analyzed using the Paired Samples t-Test and Cohen's d, which revealed the positive effect of LPCR with a medium effect size. Also, students' attitudes toward LPCR were assessed through a seven-point Likert-scale questionnaire and semi-structured interviews, employing the Technology Acceptance Model (TAM) as the theoretical framework. The results indicated that, on average, students considered LPCR useful and easy to use, and they had positive attitudes toward using LPCR and behavioral intention to use it. Additionally, the results of a path analysis with the students' questionnaire responses showed both significant and non-significant direct and indirect effects of the four TAM variables: perceived usefulness, perceived ease of use, attitude toward use, and behavioral intention to use. Pedagogical and research implications are drawn from the findings, and recommendations for implementing LPCR in future instances of English grammar instruction in synchronous online classrooms are offered.