A great way to introduce new vocabulary to students of any level is James Asher's TPR, or Total Physical Response. By giving commands to students, just as a mother gives commands to her baby, students learn to listen and comprehend naturally. By the end of a typical lesson, students are able to give commands to their classmates, turning a listening activity into a speaking activity. You can supplement TPR with other activities to help reinforce the vocabulary you want to teach. Try googling "Total Physical Response" for more information and sample lessons.

Joe

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You can have a combination of various methods to introduce vocabulary. One way is to teach them about the roots, prefix and suffix. Give them commonly used structures in different situations. You can also list down all the possible structures with reference to Imperative and Exclamatory sentences. Make them go through interesting reading material. Ask them to guess  the meaning of the words they do not understand  taking the whole sentence into consideration. You can then tell them the precise meaning and ask them to make a sentence using that word which should be checked by you immediately.