The first thing you should do is try and match the children's energy levels and speak over them to get their attention.
This should usually get their attention however if it doesn’t, you should ask the nursery staff to get involved with the session and help with managing the children’s behavior.
You can do this by putting the children in a small group or literally asking the staff member to take part in the session assisting the children that are struggling and disrupting the session the most.
If you find yourself with a group of young children that are not listening you should always seek the nursery staffs help as at the end of the day they are young children and they will behave differently each week on occasion.
If in your nursery sessions, nursery staff are regularly not getting involved or chatting on the side report it in your session review.
A lot of nursery managers ask and encourage their staff to get involved and always ask for feedback so any feedback you can provide helps us build rapport further.