The purpose of the study is to determine whether the solitary and tablet assisted presentations of direct instruction method differed in terms of efficiency and effectiveness in teaching science topics to students with intellectual disabilities and to obtain the opinions of participating students and their real-time teachers about two different instructions. The participants were four male students who had been diagnosed with intellectual disability. Adapted alternating treatments model, among single-subject research designs, was used in the study. The research findings indicated that the solitary and tablet assisted presentations of direct instruction method were both effective in teaching respiratory system and digestive system topics to students with mental disabilities, the participants could generalize what they had acquired to different settings and people, and they preserved what they had learnt 10, 20, and 35 days after the instruction was over. The productivity findings of the study implied that the tablet assisted presentation of the direct instruction method was more efficient. Social validity findings uncovered that students and teachers had positive opinions about the study.