Sometimes you can make a connection for the kids by sharing campus traditions that you remember like the zodiac, the campanile, your dorm/apartment/greek residence, any building that you spent the bulk of your time
haunting. Like someone else said, visit the admin office of the department(s) housing the major(s) your kid is interested in. If you go online, most departments have someone who does the recruiting of undergrads, or a lead departmental adviser...contacting them directly, you can often get a personalized tour of the department, and they can arrange brief visits with faculty in the area of interest. I see family tours in our department on a daily basis all summer.
I believe they may offer campus tours, but I think those are part of orientation (which is of course for students already accepted/enrolled for fall). Here's a link to what Admissions has to offer:
http://www.admissions.iastate.edu/visit/
Good luck - I hope you have a second gen Cyclone on your hands.