Disadvantages
*Starting the lesson with a grammar explanation may be frustrating for some students, especially younger ones. They may not have sufficient metalanguage or may not be able to understand the concepts involved.
*Grammar explanation encourages a teacher-fronted, transmission style classroom.
*Explanation is seldom as memorable as other forms of presentation, such as demonstration.
*Such an approach encourages the belief that learning a language is simple a case of knowing the rules
*Time and energy spent working out rules may mislead students into believing that rules are the objective of language learning.
*It can place heavy demands on teachers in planning a lesson