If you're organizing a field trip for the schoolchildren, you surely need to collect all the parents' formal consent. Doing this via an online form is way more convenient than using traditional paper slips.
First and foremost, the legal guardians might fill out the field trip permission form from the comfort of their homes (instead of visiting school just to hand in a piece of paper). Secondly, the electronic consent submissions cannot be easily lost, unlike their paper counterparts.
The form template below already has all fields that you might need. Click the button "Use this template" to make it yours and start customizing it.