One important element when I am presenting my lesson is an attention grabber that is also relevant to the content. Research shows that the average attention span of an adult is about 20 minutes. Every 20 to 30 minutes, I use a progressive form of the attention grabber to keep my students motivated. But I also find that some students' attention span vary from 5 to 15 minutes and they need individual motivation to continue to work on the labs and exercises. I have to do a combination of group teaching and individual assistance to keep the class moving. I'd like to read other teachers' experiences on maintaining their learners attention.