this question reminds me a quiz program, which uses multiple pages.
make a database, where you can fill questions - properties - page numbers.
the user have a question in the first page:
Your Email address, send a link to that email, if the user filled all the question from the page 1, ask the second page's questions.
use database to store the previously inserted values, but the authentication uses email/password:
you send a password to the email address, with that password the user can continue the "Quiz"
The complication in this project is the previous answers button
You have to handle more properties:
-updatable field
-update only if the user validated it with his email address, this need a historical database model!
-not required field