I don't know if your students are anything like mine, but if they are, there are days that getting them focused and paying attention is a losing battle. Even if they are quiet, gettting them focused and attentive is a different story!
Here's a strange thing that some of us in my department have been noticing lately. Students pay attention to a video clip much better than they pay attention to me. I have used this in a few different ways:
-- using video clips such as this that I have found online, and then creating a guided note sheet, questions, or an assignment to go with it. Here is one example of a great instructional video. http://m.youtube.com/watch?v=qhvSX0-I9N8. There are a lot, usually about 5-10 minutes long that can replace notes, introduce a topic, or reinforce notes. It's similar to the idea of the flipped classroom, in a way, except I'm doing it in class in this case, student can watch together in the board, or in their own on device,depending on the time you want to spend, and the structure of your class/access to technology. Kids say to me things like "remember on Friday in the video when that man was talking and he said...."
-- I have also created or found some even shorter video clips and photos to give lab instructions, and to show a model of something. It's big, easy for everyone to see, and they can rewind if needed. For example, I made a video of making the onion cell slide. Not great, but it was my first one. Easily filmed with a cellphone, tablet, webcam. For some reason, they seem to remember.