Teaching a dog to play.
I recently resucued a german shepard/lab cross from the pound. She has been there for at least a year and is around 2 years old. I'm not sure where she was before she was put in the pound. She is very well behaved and besides a few kennel related issues she's fine.
But she doesn't seem to know how to play. I have a ton of toys here, tennis balls, bones, rope things, noisy things. She just ignores all of them. She also won't chase balls when I throw them.
How do I teach a dog who obviously missed out during puppyhood how to play?