Assuming the school has a valid need for this information, and you are happy to provide it, this is probably one of the better ways to collect it. Compared it to asking for this via email, or paper form that then gets entered into a school computing system. Email is sent in clear text, anyone sharing the same network can see this traffic, including your ISP and the schools ISP. A paper form could get lost on the way to school or in the post, and once entered into the computer probably will get put in the rubbish, not shredded.
Googles servers themselves are very secure, the web forms are also very secure. I would be much more worried about the schools information security, irrespective of how it is collected.
The following are the questions you should be asking the school.
- Why are they collecting this information and what use will it be put to?
- Who have they given permission to view this information?
- Do they require all those people to have two factor authentication on their
- Do they require all those people to only access
their Google accounts on fully patched computers?
- Do they require all those people to run up-to date
anti-virus and anti-malware programs?
If I was a bad person wanting to get hold of this information I would not attack Google I would attack the machines/accounts in the school which have access to the information. This would remain the case no matter how the data was gathered as long as it was stored electronically.