Every page on this site is sized to print cleanly on both US Letter and A4 — you don't need to change your paper size setting. A few tips to make everything look its best:
Regular printer paper works fine for trivia cards, recipe cards, and activity sheets. For place cards, wish cards, and anything you'll fold and stand up, cardstock (65–110 lb / 176–300 gsm) holds its shape much better.
Print at 100% scale — do not use "fit to page" or "shrink to fit," since every page is already sized with a safe margin for both Letter and A4. Color printing looks best, but everything is designed to look good in black-and-white too.
A ruler and a craft knife or paper trimmer gives the cleanest edges along the dashed cut lines, but regular scissors work well too — this is meant to be a kids-can-help kind of craft.
Score fold lines first by running the back of a butter knife or a closed pair of scissors along the dashed line before folding — it makes for a much crisper, straighter fold.
Every page is built to a shared safe area that fits inside both paper sizes, so whichever your printer defaults to, nothing will be cut off.
All the artwork here is line art on purpose — clean outlines instead of solid color fills — so these pages use very little ink even printed in full color.