Currently you are able to search by school rating and grade level by enabling schools in the filters tab.
Here are instructions on how to do so:
1. Log in to your Zillow app
2. Type in the location desired into the address bar
3. Go to "Filter" >> Switch 'Schools' to ON >> choose your criteria
4. Check mark 'Only show homes matching all criteria'
From here, you can click on the school of your preference to view homes within that school zone by selecting the option "See homes in this zone."