Packing a lunch a child will actually eat is half the battle. The other half is making sure it still holds up by midday — no soggy sandwiches, nothing that needs reheating, nothing that spoils if the bag sits in a locker for four hours.
Start with something that travels well. A wholegrain sandwich holds together better than white bread, and swapping mayonnaise for hummus or avocado stops the bread going mushy by noon. Cut it into quarters — smaller pieces get eaten, whole sandwiches often come back half-touched.
Fruit is the easy win, but pick ones that don't need a fork. Dates are one of the few fruits that travel at room temperature without bruising or leaking — no container needed, just a few in a small bag. Sayer or Piarom dates keep their texture through a whole school day, unlike sliced apple which browns or grapes which get squashed. Other dried fruit works the same way if a child wants variety.
A small protein source rounds it out — a boiled egg, a few cubes of cheese, or a handful of nuts if the school allows them (check the nut policy first; many don't). Add a vegetable that survives being packed: carrot sticks, cucumber batons, cherry tomatoes cut in half so they don't roll away.
Skip anything that needs the fridge right up until lunchtime unless the bag has an ice pack — yoghurt and soft cheese spoil fastest in a warm bag. Keep the treat small, if there is one: one biscuit or a square of chocolate does the job without turning lunch into dessert.
The formula that works day to day: one carbohydrate, one protein, one fruit that survives the bag, one vegetable, and water instead of a juice box. Pack it the night before if mornings are rushed — a lunch made at 7am under pressure is the one most likely to end up all crackers and nothing else.