When it comes to teaching vocabulary for second language learners, there are several factors which should be carefully considered so that teachers can reach the effectiveness of delivering new items to learners.

1. The number of new words presented

The number of new vocabulary words presented should not overstretch the learners’ capacity to remember them. Nor should the presentation extend so far into the lesson that no time left to put the  vocabulary items into practice.

In order to decide how many words to teach, this will depend on the following aspects:

• The level of learners (whether they are beginners, intermediate, or advanced)
• The difficulty of the words (whether they carry abstract or concrete meanings, or how challenging they are to pronounce)
• Their teachability (whether they can be easily explained or demonstrated)
• The likely familarity of learners to the items (whether they have seen the words before though they may not use them in speaking or writing)
• The aims of presenting the items (whether they are used in writing and speaking or used in listening and reading, for more time will be required for the former.)

2. The sequence of presentation 

There are a widely argument of whether meaning should be presented first, then form, or vice versa.

As for the first choice, introducing the meaning first creates a need for the form, making the presentation both efficient and memorable.

On the other hand, presenting form first works best when the words are taught in some kind of context, so that the learners can figure out the meanings for themselves.

3.  Means of presentation

The meanings of the words could be presented to the learners  through: translation, real things, pictures, actions/gestures, definitions, situations. 

And teachers should also consider whether to present the meaning in its written or spoken forms.