I agree that the group time maybe needs to be kept more informal if they have been in school all day. Maybe sing some silly type songs that might not be done at school - the kind of song you sing at camp or brownies or beavers.

Games that involve the whole group such as picking a catagory and then go around the circle with each one adding something to the list. When they get stumped change the topic - ex name a colour, name a fruit or vegetable, name a country, etc.