On February 6, Education Week published a great article by Sarah D. Sparks called

 Studies Find Vocabulary Instruction is Falling Short

.http://www.edweek.org/ew/articles/2013/02/06/20vocabulary_ep.h32.html

It says, "the whole common core will fall on its face if kids are not getting the kind of instruction it will require." 

Pre-school students in poverty enter school knowing far fewer words than their peers from higher-income families. According to the article, by age 3 youngsters from high income families have a working vocabulary of 1,116 words, compared to 749 words for children in working-class families and 525 words for children on welfare. 

In a study done in Michigan by Susan B. Neuman and Tanya S. Wright, few formal structured lessons on vocabulary are given.  Instead, most teachers defined words during teachable moments that came up as they read stories to students.   That informal style led to major discrepancies in both the number and difficulty of vocabulary words introduced.  Some teachers teach 2 words a day and others as many as 20.

Words are often chosen from the stories the students are reading. 

This is common in my district.  Words are taken from the basal reader or leveled readers or the content subjects. Basal readers, at most,  introduce about 300 words a year, not enough to close the gap among children.

Studies suggest that a student needs to hear a word about  28 times to remember it.  The more sophisticated the word, the more important it is for students to have opportunities to recall it.

It seems that vocabulary instruction seems haphazard at best.  Sparks remarks --and I agree-- that vocabulary is a critical, but deceptively simple literacy skill that is essential to students' academic success. 

One of the measures suggested was to consider the Dale -Chall list, a list of over 7,000 words commonly known by 4th graders. 

Another suggestion was to concentrate on Level II words.  These are lists of words categorized by Isabel L. Beck, a professor the University of Pittsburgh.  She says that Level I words are common words and that Level III words are content area words.  Level II words are academic words such as 'categorize' and 'compare.'  Explicit instruction is an effective method of instruction.  Strategies for rehearsing and repeating new words have to be developed so that students are exposed to new vocabulary repeatedly.