I know from my own kids HS, you must show your dl before you are allowed in' then they take your picture and give you a sticker of you picture to wear while you walk 10 feet to the office, then you fill out a card with the reason you are picking your kid up, THEN the kid swipes his school id, then you can leave. It's such pain because there is usually a line to do all this. I'm thinking this is all over the US? Maybe not in CA, maybe they're more laid back.