The hard part is never building the form, it is getting the link in front of someone at the moment they are willing to answer. Nobody types a long docs.google.com address off a whiteboard, a receipt or a banner, and thirty pupils typing it wrong is thirty lost responses. A QR code removes the typing entirely: print it in the corner of the worksheet, stand it by the till, staple it to the permission slip, put it on the conference lanyard card or the waiting-room poster, and the form is one camera-point away. That timing is the whole advantage over emailing a link later, because at an event you are competing with the walk to the car park, and afterwards you are competing with an inbox.
Two details decide whether the printed code actually works. First, the form has to be published. Google's current model separates writing a form from opening it to responders, so a code made from an unpublished form scans into a dead end. Second, a Google Form has two completely different URLs and only one of them is safe to print. The responder link contains /d/e/ and ends in /viewform, or it is the short forms.gle version, and it opens the fillable form. The edit link ends in /edit and is what sits in your own address bar while you write the questions, which is exactly why people copy it by reflex. Anyone scanning an edit link hits a request-access wall and cannot answer. If the link you are about to paste ends in /edit, stop.
After that, remarkably little can go wrong. The responder link is keyed to the form's ID, so editing a question, retitling the form, changing the theme or adjusting the settings issues no new URL, and one printed code can front a form you keep rewriting all year. Three things do break a code already in the wild: unpublishing the form, which makes the link inaccessible to responders, deleting it, and using 'Make a copy', which creates a different form with a different ID and therefore a different link, so edit the original instead. QR Cake codes are dynamic, and dynamic is free here, which gives you a fallback the raw Google link cannot: save the code to your account, then open it in your dashboard, paste a different responder link, and every copy already printed follows. That is how last term's trip consent form becomes this term's, and how a pre-event sign-up form becomes the post-event survey with nothing reprinted.
