How long it takes to reach Iguazu Falls from Buenos Aires?

Can someone tell me How long it takes to reach Iguazu Falls from Buenos Aires? I need to know how long is the travel because of my children. They dont enjoy traveling very much, so I wouldnt like to bother them. Especially the younger one has problems while traveling. So please give me this info, as soon as you can . Thank you in advance.

I have never been there, but my sister was. I know that he has some really nice pictures from Buenos Aires and Iguazu falls. She was there a year ago. I dont know how long exactly she traveled. But I know that she has some really bad memories about that trip. They transportation had an error, and they waited 3 hours for someone to come and help them. But my sister is a person that likes to joke with everything. She looks on this event like on some kind of adventure. And now we are laughing when we mention it. But dont let this to discourage you. That is only the bad luck of my sister.