There are times when I have distributed a learning activity when they return from break/lunch based on our discussion prior to going on break/lunch. I give them a specific time frame (10-15 minutes depending on the length) to complete the activity for some possible extra credit points depending on the difficulty of the activity. Those students who do not come back from break/lunch on time also can participate in the activity, however, they have lost minutes because they were not back from break on time. I have found since beginning this, the students tend to come back from break or lunch on time as they do not know when/if there may be an opportunity for extra credit.