Classes are powerful, but you don't need them for everything. A simple guide:

Reach for a class when you have a "thing" that bundles data and actions on that data, and you'll make several of them — students, accounts, products, game characters.

A plain function (or dict) is enough when you just need to transform some values once. Don't wrap a single calculation in a class for no reason.

Rule of thumb: start simple with functions. Reach for a class when you notice yourself passing the same group of values around together again and again.