when we puppy sat my friend's puppy (totally soft and adorable labrador) she was 5 months old and we had her for a few days, and my friend's dh taught our kids how to do some training with her.
so, one child at bottom of garden and one at top, the kid at the other end starts to call puppydog, come here, come on, good girl etc. Puppy races down garden to lots of fuss and attention, then the child at the other end repeats. So she was learning that when her name is called she gets loads of fuss.
When she was older we did it out and about, same thing, two people a distance apart. It worked like a dream.
We started off with steppedog that way too, when we first let him off the lead, so he would come when we called. Mind you for steppedog is took a little longer must be because he is an adult, and nothing to do with him being a stubborn git