Why does vocabulary knowledge vary?

Why does vocabulary knowledge vary?

Why do some students have a richer, fuller vocabulary than some of their classmates?

Language rich home with lots of verbal stimulation
Wide background experiences
Read to at home and at school
Read a lot independently
Early development of word consciousness

Why do some students have a limited, inadequate vocabulary compared to most of their classmates?

Speaking/vocabulary not encouraged at home
Limited experiences outside of home
Limited exposure to books
Reluctant reader
Second language—English language learners

Vocabulary. (2017). Retrieved July 15, 2017, from https://www.readnaturally.com/research/5-components-of-reading/vocabulary