structural syllabus:  A syllabus in which grammatical structures form the central organizing feature. A structural syllabus proceeds from simple grammatical structure to more complex grammatical structure. An example might be something like: Present progressive -> Comparatives -> Simple past -> Past progressive. The main faults of structural syllabuses is that they tend to ignore meaning and a lot of really useful language is neglected at the beginning because it is viewed as structurally too complex (If I were you, I would).

Structural syllabuses can be contrasted to functional syllabuses, which are organized according to the functions that language has (greeting, asking advice, disagreeing).

http://bogglesworldesl.com/glossary/structuralsyllabus.htm

What is grammatical syllabus?

Grammatical syllabus refers to the syllabus in whish grammatical criteria will be used to break the global language into discrete units. The items will be graded according to the grammatical complexity and simplicity of the items, their frequency, their contrastive difficulty in relation to the learner’s first language, situational need, and pedagogic convenience. (Wilkins,1976)

The problem faced in determining the grammatical content are more those of selecting and grading. The linguistic criteria that are most often cited in relation to the grammatical content of teaching are: simplicity, regularity, frequency and contrastive difficulty. Judgements of the simplicity are mostly made according to the “learnability”. Criteria of regularity request that the most productive linguistic structures should be taught before those of low productivity. The notion of frequency is self-evident. Contrastive difficulty refers to the degree of difficulty in relation to the learners’ first language. From this point of view, we can say that the syllabus that results from the application of these criteria will be grammatical syllabus.

4.      Merits of grammatical syllabus

(1)   It is “economic”. In natural learning, such as learning one’s first language, the amount of time and motivation devoted to learning is great. However, in classroom study, there is very much less time available, and often less motivation compared with the “natural learning”. Therefore, learning time should be organized carefully for efficiency. This means preparing a program of study-syllabus-so that bits of the total corpus of knowledge are presented one after another for gradual, systematic acquisition, rather than all at once. Also it means preparing an organized, balanced plan of classroom teaching /learning procedures through which the learners will be enabled to spend some of their time concentrating on mastering one or more of the components of the target language on their way to acquiring it as a whole. Thus we can benefit from the grammatical syllabus.

(2)   It is “systematic”. Language is highly systematic in grammatical syllabuses. Language is produced in accordance with a complex system of rules. As for the approaches to language teaching is such syllabus, according to Prabhu (1987), are base on “internalization of the grammatical system through planned progression, pre-selection and form-focused activity”.

(3)   It is “easy”. For teachers, it is easier to mater teaching methods and to operate them in class under such syllabus, for the teaching skills are comparatively easy. And it is easy to evaluate how learners go on with their learning, because the evaluation criteria are simpler than that of other syllabuses. As for learners, all they need to do is to memorize the rules and make grammatically correct sentences. Therefore, it is a little bit easier. Learners do not need to master many learning strategies.