Its a good chance to sit in Kinnick, eat some popcorn, and watch the players on the field.
Here is last year's info:
http://www.hawkeyesports.com/sports/m-footbl/spec-rel/081313aac.html
Your kids are pretty young, so you'd want to get their early to do the Kids Zone stuff.
Players sign autographs after the practice, but your kids are probably too young to get there early and stay through to the end for autographs. I'd go for Kids Zone, watch 30 minutes of practice, walk around stadium a bit, then get out of there.