My daughter asked why I always put the snack bags in her lunchbox but pack the sandwich in my purse

Look, the snack bags go in the lunchbox because that's where they belong—visible, organized, ready for lunchtime.

The sandwich goes in my purse because I need to remember to actually make it.

Punchline

It's called a backup location system. The snacks are committed, but the sandwich is still in the "maybe we'll grab something on the way" phase of meal planning.