In the US, in the weeks leading up to the new school year starting late August/early September, many retailers will offer discounts on school supplies - paper, pencils and pens, backpacks, etc - to attract customers. Many clothing retailers market it to students as a great time for a wardrobe refresh or to reinvent your look entirely and offer discounts. Same deal with electronics, especially since higher math courses tend to have required calculators. Some states - including Ohio, where I live - offer a sales tax holiday on a weekend during this season to help with the expense involved.
It’s wicked expensive with just one kid, I can’t imagine having several.