8GB USB sticks are on sale in the AV room
USB sticks are great for transferring documents between computers, but they're not entirely reliable.
Don't keep your only copy of a document on a USB stick. Keep a copy on the computer. The safest place for a document is in your documents folder on the school's computers.
Use the "Safely Remove Hardware and Eject Media" tool on the taskbar near the clock to stop a USB device before pulling it out of the socket. Just removing it without stopping it can cause loss of data.