ESLには週1〜２回開催される定期開催クラスと、登録不要で単発のウォークインクラスがあります。定期開催クラスは教える先生によって授業内容が大きく異なり、使う教材も進め方も全く異なります。また、先生の知識量ややる気もまちまちなので、そのクラスが有意義なものになるかどうかは先生によると言っても過言ではありません。ただ、人気のある先生はすぐ異動しがちです。私の2人のお気に入りの先生はそれぞれ1セメスター（3ヶ月）、3セメスターで他の図書館や大学に移ってしまいました。先生の質は授業を受けてみないと分からないので、新しい良い先生を探すのも一苦労です。
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ESL has two types of English classes, one is a series-based class that is held once or twice a week, and the other is a walk-in class that doesn't require registration and is one-time completed. The contents of the class, including the material used in the class and how to proceed incredibly, vary greatly depending on the teacher. Also, the amount of knowledge they have and how much they are motivated vary depending on the teacher, so It's no exaggeration to say whether or not the class will be meaningful depends on the teacher. However, popular teachers tend to be transferred to another place in a short time. My two favorite teachers were transferred to another library or a university after 1 semester (for 3 months) and 3 semesters respectively. Since I can't find out the quality of the teacher until I take classes, It's a little hard to find a new good teacher.