With all the preparation and planning outlined above, you should be ready and eager to meet the students face to face. So, like you planned, arrive early, get checked in at the front office, and bring your materials to the right place.
You will be a curious distraction as soon as students notice you. If you have some time to wait, you can prime their curiosity with hints about the activity. If you need help setting up, you might ask for volunteers to hand out materials, re-arrange chairs, etc.
Once things get going, be as confident and comfortable as you can. You can break the ice by having the students talk a bit first. Ask the class some questions about the topics in the activity or related material they have covered in recent class work. You can then guide the discussion toward the issues on which you hope to focus. Don’t be afraid to call on the teacher, too.
Always try for a positive, open-minded flavor in the discussions. Promote inquiry and self discovery, of both questions and answers. You may need to bring the focus back to the key issues, but remember those off-topic questions for future visits. And don’t be afraid to admit that you don’t know all the answers. You can best represent science by showing how un-answered questions can provide the motivation for new research.
At any grade level, you may encounter challenging or even controversial situations. Questions about the age of the Earth, the origin of species, the environmental impacts of resource development, and other touchy topics can put you in the hot seat. You will have to decide for yourself how to answer, but avoid telling students that a particular view or belief is wrong. You can try to narrow the discussion to what physical data and scientific analysis might conclude, and decline to offer philosophical or political opinion. More than one teacher has deflected religious issues by telling students they can be “fired” by breaking school rules.