Vocabulary instruction in content areas is extremely important.  In the article titled, Research on vocabulary instruction in the content areas: implications for struggling readers, Harmon, Hendrick and Wood (2005) discuss the challenges that teachers face when instructing content areas.  In content areas most of the vocabulary are tier 3 or low frequency words which do not regularly appear in other contexts.  Many students struggle with the textbooks offered in content courses because they can not access the language being utilized due to insufficient vocabulary knowledge.  Students who have early and intensive exposure to words are more likely to have a greater vocabulary than those students who have had limited exposure.

Struggling readers in the content areas need not only vocabulary assistance but also need to be taught reading strategies that will help them to access the text.  Students must be able to understand the vocabulary of a content area so that more complex concepts can be addressed.
There are many effect strategies that teachers can use to increase comprehension of content vocabulary.  Graphic organizers accompanied by in-depth discussions, provide opportunities to use new vocabulary in many language modes, and actively engage with the language.  Teachers can help students make real world connections to the content vocabulary.

In science, teachers need to ensure that students are familiar with and can comprehend tier 2 words that are non-technical.  I know that I am guilty of assuming that my students are coming to class with basic science language but this is not always the case.  I know in the coming year I am going to focus more on these tier 2 words and meanings hoping to provide more access to the tier 3 words and science concepts being taught.

The authors conclude the article with suggestions for helping struggling readers which can be applied across the curriculum.  They suggest providing opportunities:
 to engage in independent reading
relate below grade level trade books to content area
use contextual-base approaches
encourage independent learning by allowing students to self-select terms for study
teach key vocabulary
provide opportunities for multiple exposures to key terms
avoid drill and practice activities
emphasize structural analysis when teaching vocabulary
provide staff development training in effective vocabulary instruction

I find this last statement an area where probably most school are lacking.  Teachers are not effectively teaching vocabulary nor are they trained to do so.  "Ensuring that students have a conceptual understanding of content area vocabulary is essential for success in all subjects." (Harmon, Hnedrick, Wood, 2005)