Optional courses can be defined as the ones that allow students to select what to learn freely according to their own characteristics and developing direction, thus fitting for students’ personal difference。 Besides compulsory courses, based on learners’ interests, hobbies and aspirations, optional courses are to broaden their knowledge, develop learning abilities, train inpidual specialty, reach full potential, cultivate the spirit of conscientiously study and aggressiveness and strength social bonds (Lv Da, 2004)。

And Palmatier and Martin have such an understanding: an optional course is one chosen by a student from a number of optional subjects or courses in a curriculum, as opposed to a required course which the student must take。 While required courses (sometimes called "core courses" or "general education courses") are deemed essential for an academic degree, optional courses tend to be more specialized。 Optional courses usually have fewer students than the required courses (2015)。论文网

Optional courses are regarded as continuation and supplement of the compulsory course。 The relation is mainly manifested in the following two aspects。

First, optional courses are equal to compulsory ones in terms of curriculum value。 There is no primary-secondary sequence between them, and optional courses are not dependent but a relatively independent curriculum 

Secondly, optional courses and compulsory courses complement each other, composing the organic one on the whole。 Compulsory courses do not exclude selection。 In the long run, they foster abilities needed for students’ free choice。 And in the process of learning compulsory courses, inpidual discrepancy is also supposed to be respected; personality and special skills are encouraged to develop; rational and valid selection of learning content and methods by students themselves are assisted。 The thought that optional courses are casual or desultory is wrong because those courses are organized and carried out with the guidance of relevant standard-evaluation。 

Zhang Hua (2000) argues that optional courses and required courses are not only relatively independent but also united with each other and both of them are counterparts of personalized course system。 

Optional courses are characterized as three obvious features: selectivity, complexity and guidance。

Selectivity concerns about students’ independent choice of courses, which is the core of optional courses。 It contains two opposite meanings, selecting what to learn and giving up others。 A vital point is that selectivity of optional courses means students’ freedom to choose a certain course instead of prescribed arrangement by instruction administrators (Ren Changsong, 2002)。 In this sense, selectivity of optional courses is same as autonomy of students。 

Complexity contains persity of optional courses and complication of teaching。 On the one hand, a wide range of optional courses represents variety。 The more optional courses are offered, the wider alternative is provided for students。 For instance, students are required to complete three optional courses but there are total three optional ones being optional。 Optional courses in true sense must be multiple。 On the other hand, the difficulty level of teaching management of optional courses is much higher than compulsory ones。 Students from different classes have distinct academic performance and they don’t know instructors very well ahead。 It is a big challenge for teachers with various teaching styles。 

Compared with prescription of compulsory courses, guidance of optional ones is a limitation for students’ degree of free choice。 The leading role of teachers does not be weakened in optional courses。 To fulfill the responsibility for students and avoid their selecting courses with blindness, it’s of utmost necessity for schools and teachers to provide proper guidance including introduction of credit, scheduling, evaluation mode and so on。 The phenomenon of students’ electing optional courses at random to meet the requirement of credit would be under strict control。