Save Icon?

I enjoy learning things like this. Above is a screen shot of one of Office² HD's documents. Notice the floppy disk icon. I kept telling my 6th grade students to tap it to save their documents until I noticed that very few of them have ever even seen a floppy disk! Most didn't know what a floppy disk was and I didn't have one handy because I haven't used one in years! What icon should software developers use for Save??