I was asked by a number of members to share an example of one of my self grading interactive PDFs. So here is very basic version that you can modify for your own use.
I included a blank template that is secured with the exceptions being the ability to fill in fields and make comments. I set it up this way so the student can't reformat the quiz. I use to use MS Word but without fail I would quizzes back where the student would delete all the questions and just give me answers (sometimes I would just a single paragraph for a 20 question quiz!) or change the typefaces, etc.
To enter your own questions into this template go to properties and use the password EDEX1 and then edit text under the tools option.
I also included a graded example of the template and here you can see the text fields that the student uses to reply to a question are scrollable so if they need more room it does not reformat the whole quiz. So when I get a quiz back from a student I just check off the correct answers and then add audio feedback (look for a mic in the upper hand conner on the graded example) for any incorrect answers.
The problem is you can't protect just the check boxes so a student could check these boxes and in effect grade their own quiz. To avoid this a solution is to mark the check boxes as read only so they are "invisible" and the student can not select them but this will require you to go in and turn off the read only option before grading. I chose to simply tell the students that the boxes are for my use only (a tool tip will also appear if the student moves their cursor over the box instructing the student the the box is "For Instructor Use Only") and not to check them because the whole reason of making the quiz self grading is to speed up the grading process and the time added by having to go in and change them back from read only would defeat the whole purpose of making grading quick and easy.