Multiple forms or everything in a single form?

I am building a school test managing web application in PHP and JavaScript (jQuery). In a nutshell, teachers can make tests with multiple tasks and students can solve them, and the system would evaluate the tests. Creating a testsheet is easy (title, description, class, subject etc.), it's one form, I submit it, and I insert the data into the database. But there's this part, when a window comes up to create the tasks for the previously created testsheet. Each task has attributes (the question, type of the task, possible answers etc.). I think it is really similar to Google Forms.(As far as I inspected Google's method, they did't even use forms.) How should I make this? Each task needs a new form (like create one task at a time, submit it, and user clicks 'Next', and a new form comes up), or all the task should be created in one form? (all task boxes are listed when the page loads) But in the latter case, how can I handle the POST data in PHP? Thanks in advance.