tired aussie mix

Question
I just adopted a 6 month old Australian shepherd mix from a local shelter.  
He's very sweet and seems to be very smart.  He loves playing with other
dogs and loves going on walks.  However he seems to not understand how to
play with humans.  He doesn't at all know what to do with a tennis ball or any
other kind of non-chew toy.  Is there some way to train him to play fetch or
tug of war or something?

Thanks for your advice!

Answer
Some dogs just aren't that drive-y and aren't crazy about balls or tug.  But, that doesn't mean you can't have any play type fun with your dog.
Why not teach him some tricks (you can teach him to fetch this way, too).
First, get your dog used to being trained with a clicker:
www.clickerlessons.com
Once he is basically clicker savvy, you can teach some tricks:http://www.dogplay.com/Activities/tricks.html
Trick training is fun, and has the added benefit of tiring the dog out just like play does, improving your relationship (everything is done using positive training), and you can show your very smart dog off to your friends.
Here's how to teach the retrieve to a dog that doesn't have much interest.  (My dog was taught with a dumbbell - she still doesn't retrieve balls or sticks, because I didn't use them when training, but she has never, ever failed to bring me back that dumbbell!)
Good luck.