The lunch box that survives a crowded backpack is hard-sided and rectangular

A hard-sided, rectangular lunch box with a slightly domed lid is the most crush-resistant thing you can put in a crowded school backpack.

Soft lunch bags are the obvious loser here. They’re made to flex, so every math textbook turns into a sandwich press. A hard-sided box made of metal or thick plastic at least gives you a structural shell.

Go rectangular, not round. A flat bottom sits stable in the pack, and the wide lid spreads the weight of books evenly instead of letting one corner dig in. A slightly domed lid is better than a dead-flat one because it deflects pressure like an arch. Thin plastic bento boxes still cave; you want thick walls or metal.

Also make sure it fits snugly. A little box rattling around under a pile of stuff takes hits from all sides. You want it wedged in there, not loose enough to get battered.

Your kid’s sandwich will be a lot happier if you buy the rigid box.