The agricultural community needs to encourage farm tours for youth for educational purposes. First, contact your insurance carrier to make sure your operation is covered for educational tours.
Consider that there may be some health risks to both the children and the animals related to tours on farms. At the very least, you should provide hand-washing stations with plenty of water and soap. If there is no water available, provide hand sanitizers and encourage children to use them.
You may want to include other biosecurity measures, such as foot baths, disposable boots, cautions about touching animals, etc.