There are many emulators available, but the one that has the least licensing restrictions is QEMU. You can get the latest Windows port of QEMU at http://lassauge.free.fr/qemu/.
Download the latest “Lite” version ZIP file and uncompress it. I suggest that you uncompress it to a thumb drive or external hard disk drive. This way, your VM will be very portable and you can continue working on your assignments on just about any computer. An external hard disk drive is preferred (to thumb drives) because they are quite a bit faster.