During the day, while I'm at work, where should I put the dog?

I bought your establishing your role as pack leader DVD and have a question. During the day, while I'm at work, where should I put the dog? I teach third grade so I don't get a lunch break where I get to leave, so I couldn't take him out of the crate to let him go out and two days a week I do after school tutoring so I'm gone for ten hours. I can put him on a tie-out in the yard or there is a small fenced-in pen, it's about 12x12 area, I'm just not positive he wouldn't try to dig out since all this time he's had free run of a one and a half acre property. I just want to know which would be the better option so that I can establish my role as "leader." Because I don't think it's fair to leave him in the crate all day while I'm at work where he can't go to the bathroom.

Thanks,
Danielle