Ask the teacher what their expectations for the visit are, what they have been working on recently, and what difficulties the students might have with the content.
Learning Standards and Goals
Teachers base their lessons around learning standards and goals. Ask the teacher to provide the standards that are aligned with your visit so you know the level of understanding the students need to get out of your visit.
Ask for student-prepared questions prior to your arrival. Send the teacher your presentation in advance to get feedback on the content complexity.
Visuals and Demos
Incorporate as many visuals or demonstrations as possible. If you are presenting virtually from your place of work or lab, give the students a look around or demonstrate a technique or experiment.
Telling a student a fact does not have as much impact as discovering the answer for themselves. Help by asking open-ended questions. Students may have some hesitancy to speak up. Let the silence hang for a count of 5 if no one answers before continuing.
Ditch the Jargon and Explain Context
Remove technical jargon from most of your talks for children in middle and elementary schools. Use lay terms instead. For high school, make sure to define terms before use and allow for questions on vocabulary.