The shutter speed may not look like a fraction. It may just be a listing of the denominator of the shutter speed fractions. (ex: 250, 125, 60, 30, 15, 8, 4...).
If you are using your iPhone (or other) for your camera this semester, you would probably do yourself a favor by purchasing some sort of "slow shutter" app that would allow you to manipulate the shutter speed on your smartphone.
Options:
There are others available, as well.
Check them out, and give yourself more options for creativity by buying one.
This site (CLICK HERE) might have a shutter app for your phone.
Or this site (CLICK HERE) may have one for you.
For Android: CLICK HERE.