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.
Portal share permissions can be used to set the level of access at each portal: Admin, Teacher, Parent and Student. Just click on the icon next to the portal name to cycle through the options: 
1) A red circle with a line through it signifies 'No Access', so the form does not even appear on that portal's form list. 
2) An eye icon means view-only access. The users can see the form and its data, but cannot change it. 
3) The pencil icon means full access, users can update and submit the form data.
4) The Admin portal has an additional silhouette icon. If you set the Admin portal to the silhouette icon, you can use the Admin tab to limit access to the form to specified Admin Groups.

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.