If they arrive early, they will have more time for doing something
If the weather is fine, they can work in the garden
If it is cold, they can stay home(вообще не знаю че еще придумать к этому)
if it's rains, they can look into the street(тож сам можешь подумать, может лучше придумаешь)
If they go fishing, they can catch a lot of fish
If they visit their friends, they can have fun together
If they stay with their grandparents, they will make them happy