Vocabulary is word knowledge.
We must be able to produce and understand language, and that language can be spoken or written.
This relies on 3 main bodies of knowledge:

Five From Five provides an excellent overview of vocabulary, including its relationship to oral language, how to teach it, how to assess it, and how to support students who struggle with vocabulary knowledge.


Effective Vocabulary Instruction (Decodable Readers Australia)

This video helps viewers understand the difference between implicit and explicit vocabulary instruction. It also gives tips on selecting words for instruction and other key considerations for vocabulary programs.
According to NRP findings:
When thinking about planning for vocabulary instruction, keep the following in mind:
Vocabulary can be challenging to assess. However, there are ways to determine if students are learning to correctly define and use words that are being explicitly taught. Below are some examples from Five FromFive.

Use the Vocabulary Knowledge Scale to help students self-assess their word knowledge.