Why should we teach dictionary skills?

There are several reasons why we should teach dictionary skills.

It will give students greater control over their own learning, and shift the responsibility of learning to the student.
We are not born knowing how to use dictionaries well, thus students need to gain the knowledge and skills to get what they can from the dictionary effectively.
It helps students to disentangle information in the dictionary by making things explicit to them.
Dictionaries naturally generate a great deal of thinking about meaning and language.
If they can use dictionaries well, there will be minimal classroom disruption because teachers can rely on students to get the correct meaning.
Dictionaries can provide useful support not simply when teachers are in doubt about something but when they want students to confirm their own suppositions about something in English.
Dictionaries can serve as a focus for communication and classroom interaction.
Dictionary training can help students explore personal preferences and learning styles and may also lead students to new modes of study.

Dictionaries are not only a tool for private or individual learning problems, but they can also become a springboard to all sorts of other communicative and interactive activities. By exploiting dictionaries as a source of interaction, we can help students develop their confidence as dictionary users and as language learners. An important benefit of this is that students will be exposed to a great deal of language that will help them experience and explore it.

Many teachers understand the need to teach dictionary skills, but nevertheless do not teach their students how to use a dictionary. These are some of the reasons for this.

Many teachers assume that the students already will know how to use an English-English dictionary effectively because they believe they can already use a dictionary well in Japanese.
Some teachers are afraid that students will resist an English-English dictionary, and stay dependent on the bilingual dictionary and feel that their efforts will be wasted. Convincing a student to learn to use an English-English dictionary takes a lot of time and commitment on the part of the teacher and the student.
Dictionary work is not part of the syllabus.
Dictionary work is not considered interesting.
Teachers do not have a clear understanding of what is in the dictionary or how to introduce an English-English dictionary.
Students do not all have the same English-English dictionary so it makes training problematic.