New words enter the Passive Vocabulary of students. Students may understand meaning, especially in the specific context where they see a new word used but as yet cannot use the word independently themselves. To ensure words enter the students' Active Vocabulary, regular revision in meaningful situations is essential. It is estimated that a student needs to encounter a word 10-12 times before it fully enters their Active Vocabulary. Vocabulary, in the same way as Grammar, is learned through use. It is therefore very important to give students opportunities within the classroom to use the new vocabulary themselves. Students remembrance of words is relative to the degree which they have used the word, thus the more we get students to use words in a task of some sort - finding opposites, transformation etc - the better they will remember them. Similarly, if we involve students in presenting new words the better they will remember them. Hence, acting out definitions in a dramatic way - trip, stagger etc - should lead to deeper learning of the words. Sense memory becomes involved, taste, smell, touch etc, which further enhances recall. Discovery techniques where students have to find out the meanings of words themselves will be more effective than standard teacher presentation of new vocabulary.
There may be many words that students will not need to use actively themselves at a particular stage in their learning career and therefore they can remain in the students' Passive Vocabulary. For example, at Beginner level it is enough to know 'big' and 'small'. At Intermediate levels, you might begin to use 'huge' 'massive' 'tiny' 'minute' etc. At Advanced levels, you might use words like 'vast' or 'minuscule' to give a different shade of meaning or to adopt a more formal or academic tone. The point is that at Beginner level it is clearly not practical or useful spending time trying to get the student to use a word like 'vast'.