I find that extra lab activities make great back-pocket items. There is always something that can be done in the lab, and I can split the group up, giving the advanced students a task to complete on their own, while I work more closely with the ones that are struggling with more basic tasks.
Jokes and cartoons related to the course topic can make good back pocket items for small chunks of time. I tell the joke (or show the cartoon--making sure to credit the source, of course), make sure they get the point, and then ask why it's funny. With encouragement, they can take on the task of relating the humor and the concept underlying it to the subject matter of the day.
Agreed i also take notes to help extend the amount of info given to the students I have. to try and create back and forth conversation about the topic
I like to make notes for each section of the course material that relates to Field and things that help to reinforce why the material being learned will be important to the students in the future.
