Definitions and distinctions
3 vocabulary tiers 1. High-frequency words (of, the, is where...) common in oral and writen language - word recognition - require little formal attentions in their meaning, 2. common words that cross many contents but occur infrequently engouth that many children may not lear them without assistance (oreit, verical, stride...)
3. Technical words linked to specific content learning (genome, sine...) not common or widely used.