Note: You are currently viewing documentation for Moodle 1.9. Up-to-date documentation for the latest stable version is available here: Adaptive questions.
One of the main motivations behind the rewrite of the quiz module for Moodle 1.5 was to enable Moodle to handle adaptive questions. This is a prerequisite to being able to render question items written according to the IMS QTI specification.
Here is how the IMS QTI specification defines adaptive questions (items):
An adaptive item is an item that adapts its appearance, its scoring (Response Processing) or both in response to each of the candidate's attempts. For example, an adaptive item may start by prompting the candidate with a box for free-text entry but, on receiving an unsatisfactory answer, present a simple choice interaction instead and award fewer marks for subsequently identifying the correct response. Adaptivity allows authors to create items for use in formative situations which both help to guide candidates through a given task while also providing an outcome that takes into consideration their path.
Moodle does not yet have any built-in question types that make proper use of the ability of the quiz module to handle adaptive questions. Hopefully these will start appearing soon when the question type plug-in architecture is better documented.