Great Quality - Proofing Experience Needs Improvement

You guys did an excellent job on printing. However, the stickers are much smaller than I expected. I understand that is the customer's fault for understanding what 2 by 2 looks like. But many people ordering haven't ordered stickers before. To cater to these customers, it'd be great if you could give some example objects about the size of the stickers. For example a 1 by 1 sticker may be as large as a quarter while a 4 by 4 is about as large as a cup. Thanks