The first step in learning new vocabulary is to be able to recognise a word when you see or hear it. This is the easy part. When it comes to using new words, many students find it difficult. They believe they don't have enough vocabulary to expand on a topic.
One of the main reasons for this is they have never needed to try and think of interesting words to describe something. After learning a few simple words such as good ,bad , thing, beautiful, very and also , they stop trying to use other words because they know enough to get their message across.
After a few years of learning English they realise they need to use more complex vocabulary and simply can't come up with the exact word they need. Everything is either "a good thing" or "a bad thing" . In order to encourage students at B1 - B2 level to actually USE other words (YES!- there are words in the English language apart from good and bad) we came up with the BLACK LIST. Whenever a student uses a word from this list we (teachers and students) point out that this word is not allowed. The student is then encouraged to use a synonym, consulting the respective list when necessary.
If after learning English for so many years, the only word they can come up with is good and bad, this is a sign that there is a missing link in the learning process. We don't learn words just to show our teacher that we know their meaning. Words are meant to be used!