We have so much low hanging fruit in this industry with regards to privacy and security. The website you listed reminds me a lot of other one-dev platforms that aren't properly equipped to deal with their own volume.
If you're inviting teachers to add information about their districts and their students, you MUST take your security, your supply chain, and your disclosures seriously.
There is not enough experience in my industry to make up the difference. You're going to market this to teachers who sign up without the consent of their IT or data people, enter PII about minor children, and then get fired and that data will be invisible to my department forever. But you'll still have it, ready to lose it in your first big hack or sell it when times get tough.
I could list literally 3 other platforms designed by a lonely teacher in their spare time that could literally probably have their databases dumped this afternoon if I posted the links here. Please, be careful.