Perhaps the biggest problem with storage and retreival in the classoom is student work left on local computers.  

Every student who uses the machine has the same access to files as the student before.  This means that work left on the local machine--on the hard drive--stands a very good chance of being irretreivably deleted, modified, or copied.

Students who share their login with others or who neglect to log out of the machine when departing leave themselves open to losing everything irretreivably.

Additionally, security on the local computers is such that files stored outside specified directories are automatically deleted by the computer each time it is restarted.

For this reason, I urge students to take advantage of other storage methods.

Floppies are now considered 'legacy' devices--no longer do computers ship with a floppy drive. Computers in the high school generally do not have floppy drives.

The new de facto for transportable storage, these little units utilize an available USB port to transfer data to the computer. Capacity ranges from a tiny128 megabytes --over a hundred floppies-- to over 64 gigabytes.  

Positive aspects include reasonably low cost--under $10.00 per flash drive, small enough to carry in a pocket, more sturdy than a floppy disk.

Limitations are few, but the computer may have USB ports on the back, requiring climbing or digging around under a desk.  I have seen these units damaged when students try to utilize them as a key fob.

Students who leave the USB plugged in when they depart may lose it all.

Likely the most cost effective per megabyte, a CD-RW will hold about 650 megabytes of data, a DVD over 4 gigabytes.  CDs can be rewritten a limited number of times. DVD-R can't be rewritten.

Limitations include the number of rewrites allowed, the somewhat fragile nature of the plastic disc, and the fact that CD-RWs require a CD burner to update a file.  Saving the disc in the format of the burner program can be an issue.

Due to software requirements, writing and re-writing on multiple machines is not advised.

An old trick.  

Some Flash based players can be written to over a USB cable, some units can function as effectively as a USB flash drive for data storage.

Given the appropriate software and a connecting cable, files can be stored on the phone or the expandable memory chip in the phone or tablet.  

I'm not particularly recommending this method because the phone can be turned into a 3 ounce paperweight if the file system is damaged.

Newer phones often have removable flash memory which can be read and written to by a flash card reader attached to a computer. 

Expanded memory is small, expensive and easy to loose or damage.

Another handy method of storage is file forwarding through email, or attaching a file to an email message.
 
Limitations include limited file size--often smaller than a single word processing document or large format pictures.  

Caution when copying a document or image into the body of an email.  Some email providers modify the size and format of the file as it is transmitted, meaning the file may look different at the place it it received than it did where it was transmitted.  

Particularly true of images which may be reduced in size by the email provider.