The academic language of science includes science content words and words that describe the practices of scientists. The present study examined science vocabulary knowledge and science vocabulary instruction practices of pre-service teachers enrolled in a primary science methods course. This exploratory mixed-methods study presents quantitative data of the pre-service teachers' personal science vocabulary development during their science methods course including science vocabulary instruction strategies in science lessons taught to peers. Despite significant science vocabulary knowledge growth over the course of the semester, there were inconsistencies regarding their applications of science vocabulary and vocabulary instruction strategies. Interviews reveal the challenge of attempting to disrupt years of memorization strategies for learning science vocabulary. We conclude with recommendations for science teacher educators.