It all depends on what kind of begonia it is as to whether you can keep it as a perennial. There are annual and perennial begonias, but those called "wax begonias" are usually annuals. I've been able to overwinter the in your area by keeping them in a container and bringing them in from the cold, but even at that, they eventually died after a couple of years. Could you post a picture, or if not, a link to a plant like it so we can advise you better?

It didn't come with a tag, just planted in a shoe the teacher had us send in.

Gosh, and you ditched the shoe? Just kidding. Lovely plant. I suggest you plant it in a shady place where you would like to see it growing - but break off a couple of stems and start some backups. Maybe years from now you will be able to point to the offspring of this plant gift from your child.

Any idea how big I should expect it to get?

It's planted in the ground on the both side of a courtyard wall that gets southern sun). I can cover it if it is going to be cold or ppt it up and bring it in for the winter. I think it was in a 6 inch pot. I know exactly what you mean about the silvering? I didn't know it was good to let it get to that stage. I thought I was being a bad plant mama.

I'll definitely take cuttings. It will be fun to se how long I can keep it going.

Be sure to remove the faded blooms and don't let it go to seed, or it will die. You'll know if it's going to seed. The seed pods have three sides. Just pinch them off.

Some time ago I asked a question on the begonia forum, it was interesting to get some good answers...

http://forums.gardenweb.com/discussions/3962020/id-please?n=21