Verified answer

The Moon can be covered by the nail on your little finger at arm's length. This may sound surprising, but it is accurate, and it's that way all year every year. That's much smaller than a dime and a little larger than a pea. I would say it's about the size of a pea on steroids.

The moon is on? That's cute.

The moon at its full phase (and the sun btw), appears to be about a half of a degree across. At arm's length, a person's fist is about ten degrees. With that in mind, of the given objects with which to cover the moon the best would be between a dime and a pea. The example is skewed a little by the fact that everybody's arm is a different length. The little finger would be the best object to use to cover the moon because if your arm is shorter, your little finger is going to be smaller, too, so the relative angle subends about the same no matter your age or size.

... The moon can appear to be different sizes at different times of the year.. but usually its about a nickle or quarter

The tip of your thumb will do just fine.