Your kids are over 8 years old
We advise you to find out about the current temporary exhibition. For us it was The Fantastic Beasts, but they change quite regularly. Then, try to know their preferences, because the choice is wide: dinosaurs, animals, stones, birds… You can obviously spend the day at the museum, but it is likely to be a bit long for them (and for you). Choose a section and make the most of it.