We should celebrate when children have one foot in each world, childhood and adulthood. There is no one brightline that actually demarks that moment. But there are a series of small and not so small moments. One is your birthday. It’s a moment. When you’re young, it’s a big deal. When you’re older, it’s mostly not. But in between, we shouldn’t be so eager to move children to adulthood. Personally, there are more than a few times I’d trade with a 5 year old, or even my 19 year old self, any day of the week.
So a party to acknowledge that moment - that fleeting moment - is a good thing. It’s to celebrate this very moment. A moment where your child is in both worlds and not fully in either.
Celebrate life. Enjoy it. Enjoy your children. They will be grown and flown soon enough.