Ann,
I am by no means an expert–but I have learned a lot about training puppies, and will gladly share what I have learned. For example, since puppies have short attention spans–keep the training sessions short. Make it fun–lots of praise, use that silly “puppy talk” voice, and I use a lot of Pupcorn for treats. To teach “leave it” you have to watch the puppy’s body language and anticipate when they are going to go after something–like an inflated football. Then praise them when they look to you, and give them an alternative behavior like stay or come.
I taught Kodi leave it on a Sunday morning walk, everytime we came to a driveway with a newspaper in a driveway I gave him the command just before he started to sniff the paper. By the 4th or 5th paper he walked by without even looking at it and I praised him saying “Good leave it.” Give it a try see if it works for you. I will be anxious to hear how it goes.
Marcia and FLD Kodiak