There's a lot of talk lately about the necessity of teaching vocabulary for reading comprehension and academic development. While we are not refuting that all students need explicit vocabulary development, we have seen that sometimes vocabulary development can become such an isolated teaching skill that in some cases students lack a deep understanding of the vocabulary words taught. Vocabulary instruction for English learners must be highly contextualized, meaning that it must be taught in the context of meaningful instruction. It defeats the purpose to have a "word of the day" that may be isolated from anything else that students are learning. In the book "Building Background Knowledge for Academic Achievement: Research on What Works in Schools", Robert Marzano outlines eight principles of academic vocabulary development:

1.  Effective vocabulary instruction does not just consist of giving students a definition of the word, or having students look up the definition of a word in the dictionary. Students should be exposed to the word many times in the context of meaningful instruction and teachers should provide a student friendly definition of the word. Teachers should be exposed to the same vocabulary words many times through a variety of different instructional strategies.
2. Students should be able to express their knowledge of the words through both "linguistic and nonlinguistic representations". Nonlinguistic representations may include drawing, pictures, graphic organizers, acting the word out, etc.
3. Effective vocabulary instruction includes multiple exposures to key words across a variety of contexts. In order for students to retain a word in long term memory and have an in-depth understanding of words, students must be exposed to words in books, writing, poems, songs, chants, graphic organizers, and other ways. It is not enough to discuss a word once or twice and then assume that students will have completely understood the word.
4. Students need to be taught the morphology of key words, which includes prefixes, suffixes, and root words. An excellent resource for prefixes, suffixes and other words parts is the ESL Teacher's Book of Lists. It's never too early to start morphological analysis! In fact, teachers can start looking at common prefixes and suffixes with students beginning in kindergarten. It is highly recommended that teachers begin pointing out morphological similarities in cognates (i.e. words that wound the same and have the same meaning in two languages) as soon as possible in order for English learners to make connections between academic vocabulary in both languages.
5. Different types of words need a different method of instruction. Some words require more direct instruction than others.
6. Students need to be given opportunities for students to discuss the words that they are learning. Project GLAD defines this as an opportunity to have "comprehensible output" and SIOP describes this principle as "interaction" and "practice and application". Many of Project GLAD's guided oral practice strategies offer multiple opportunities to use vocabulary in meaningful ways. Teachers can also utilize many of the instructional strategies from the SIOP model of ELD instruction in order to promote high levels of practice of key vocabulary words.
7. Students should play with words through games, songs, poems, chants and other fun activities.
8. Students should be taught words that have a high chance of raising academic achievement. Marzano has put together essential lists of key vocabulary words per school subject that students need to learn. Another valuable resource for teachers is the ESL Teacher's Book of Lists and the Vocabulary Teacher's Book of Lists.

You can purchase Marzano's "Building Background Knowledge for Academic Achievement: Research on What Works in Schools", "The ESL Teacher's Book of Lists, "The Vocabulary Teacher's Book of Lists" and other related vocabulary books in the ELD Strategies store by clicking here.