assumpta you are doing a good job, please try not to worry.
Biting is normal it is what puppies do, though this can be very upsetting for children obviously, how old are they? What are you currently feeding? Are you spending specific chunks of time playing with her/training her?
It is worth remembering that a potential problem with the 'new crossbeeds' is that while temperament can never be considered a certainlty with any dog it is much less so with these as you just don't know what they will inherit. Both Poodles and Cockers are working dogs and if you end up with a puppy that has inherited a strong sense of needing to work from both breeds then you could have a puppy that needs to be kept very busy indeed.
I have friends with a Springer/Collie that has taken years to calm down and it is only by really channelling it into some serious work, he now does working trials, agility and flyball, that plus 3 hours hill walking a day keeps him relatively calm!
All that said she is really young and lots of puppies are really hyper, she obviously is very food orientated and I would definately be stuffing Kongs preferably frozen, I don't understand the 'wouldn't it go everywhere bit', I'm not sure whay your concern is? Another thing to try (if she is fed dry food) is just to feed her by taking great handfulls and chucking it in the garden or house for her to find, she can be fed all her food this way and it will be a great game for her, you need to stay with her and praise her for looking. I wouldn't ever let a dog 'play in the garden on it's own' there are too many dangers and too many cases of theft.
I gave Rudy rawhide from 12 weeks, yes it's a bit smelly and messy, but that's dogs for you
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I would just like to say that I am just a dog owner, I have a fair bit of experience in owning and looking after dogs and a very keen interest in dog behaviour and all things canine but as of yet no qualifications.