When you create a form, you have many different opportunities to share that form with different groups of people (Admin, Teacher, Parent, Student), as well as with specific Schools. In addition to sharing options, there are also publishing options.
The defaults in all these areas are to share with nobody and in no school. The publish option is also defaulted to false. By default, nobody can see the form but you, and only for modifying the form, not entering responses to it.
When creating a form, here are the sharing and publishing options:
The Publish checkbox can be thought of as a master switch, which you can use to enable or disable all sharing regardless of the other settings. The list of schools the form is shared with is displayed in the 'Shared with' box. Press to open the Role Sharing dialog in order to edit the Share Permissions.
Choose which schools the form is shared with. By default, no school is chosen for sharing. You can choose as many schools as you want.
On the Student tab you are able to refine which student records within the selected schools will have the form published to them. By default, the form will be published to all students at the selected schools.
Options for teachers are slightly different. Instead of schools, teachers can share forms with specific classes.