In Technical cl for beginners what is best way to keep them interested in the subject?

If they are not interested in what you are teaching, you should just "shoot the bull" with them for a while. Talk about something going on in the news, something that you experienced, the weather, whatever. If possible, make it funny. It will wake them up in cl and make them want to listen in case you come up with some kind of funny story. Make the cl fun by sharing some of your experiences. If you are very strict on them too much, they will tend to not pay attention. However, when you do have their attention... take advantage of it and teach the cl. When you see them nodding off, share a funny anecdote with them.