It isn't uncommon for behaviors to be bumpy after an extended break. We are always pleased if the class reconvenes with strong stamina and purpose, but experience has proven that we usually need a little refresher to get things sailing smoothly again.
We sometimes start a focus lesson with the question "What are you noticing?" Students have often recognized the decline in behavior and can offer suggestions to get things back on track.
One thing that always helps is to revisit the I-charts we created together when Daily 5 was being launched. Revisiting and even editing these foundations of independence is usually enough, but if it isn't, we repeat the 10 Steps to Independence.
Sometimes we observe to determine if a specific Daily 5 choice is the source of the trouble. If Read to Someone or Word Work is the problem area (these are usually the culprits in our rooms), we share with students that this option will be temporarily removed until behavior gets back on track. If the trouble isn't a Daily 5 choice, but is caused by one or two students, limiting their selections can really motivate them to regain their composure and independence without penalizing the whole class.
When we keep expectations high and communicate them clearly, the class soon returns to the happy hum of purposeful work that we know and love.