The teacher expects students to fill out an online form to submit weekly reports on their progress, and selects Adobe PDF interactive forms as the way to offer the forms. Students are told to use a computer with a PDF viewer, fill out the form, and submit it online.

Graphic from www.adobe.com

Many students report that the forms do not work. The problem is eventually identified as the students are using older PDF viewers which open the form and display it, but do not have the interactive form features. The students with older viewers get no error message to tell them why the form is not working for them.