The problem is externally imposed definitions usually through lecture or by supplying them before understanding has been repeatedly demonstrated in novel situations does not lead to understanding. Most science instructors know this. But most do not put this understanding into action in their classrooms because they don't know how to. Many have tried but they don't want students to form "incorrect" conceptual understandings--NEWS FLASH--that is what they come into your classroom with in the first place and giving them the "correct" definitions will not address the issue.
Some instructors might say: "I don't do that". If an instructor gives labs with a set of directions to follow that were not student created or if an instructor gives a lab after the student was held accountable in some way for understanding it (i.e. homework, worksheets, lectures, reading, etc.) then in fact that is exactly what they are doing.
Other instructors might say: "I don't have time to follow constructivist/Socratic methods (i.e. too much curriculum to cover before the test)." Coverage does not translate into understanding. I grant you that if the content tested is lower level questions and if it is heavily laden with terminology then it will be doubtful that students will do well if that content hasn't been taught. However coverage does not equate to being "taught".
Supplying carefully constructed definitions will not correct student misconceptions. Only the student can fix their own misconceptions. It is the instructor's job to create activities and SITUATIONS for the student do just that. Most instructors are masters of creating activities because this is something they have can exercise absolute control over. But in reality true student understanding does not occur in these carefully designed activities it is through the DISCUSSIONS and DIALOGUES that occur before, during, and after the activities that really matter. Science instruction needs to be thought of as less a "science" and more a "craft".
It is mentally fatiguing to craft the Socratic discussion/dialogue to arrive at the destination that you desire. Each class is different. Each student is different. The instructor has to be on top of their game at every moment to react at a moments notice to explore a student's statement that arises. I liken it to helping students to navigate a rapids. The instructor has to be in the moment as opposed to following a road map. As an instructor gets more comfortable with these techniques he/she will realize that the controlling activities they prided themselves on creating in the past actually tend to hinder NOT help student understanding.
Novice learners play and discover and make their own meaning. A thoughtful reflective mentor doesn't lecture and give definitions. The thoughtful reflective mentor converses with his/her students openly, facilitates non-judgemental conversations among novice students, and encourages introspective reflective thinking. The thoughtful reflective mentor asks probing open-ended questions in the language of his/her students in novel situations. The thoughtful reflective mentor then slowly introduces the accepted terminology of the scientific community ONLY after the students makes known to him/herself, his/her peers, and his/her instructor through open dialogue and Socratic discussion that the phenomena is understood in a variety of contexts.
The conversation is the most important part of learning--not the externally provided definition. It is through this just-in-time formative feedback and thoughtful and thought provoking discussion that the thoughtful and reflective mentor is able to be most impactful. Being able to apply the concepts behind the terminology in novel contexts and in everyday life is what counts. Being able to use the jargon is of secondary importance.