This study examines AI literacy interventions for low-achievement secondary school students in Hong Kong. Two interventions—one timetabled over eight weeks and another as a four-hour workshop—were conducted at low-resource schools. Results showed significant improvements in students' AI literacy, particularly in prompt engineering and content evaluation, with no difference in effectiveness between intervention lengths. Findings suggest that short, structured interventions can enhance AI literacy, and schools may implement co-curricular approaches to address digital divide challenges.