Aggressive Beagle Pup w/my small Kids

Question
Hi there,
My husband and I have both never grown up with dogs or had any until we recently bought a beagle (before Christmas). Our home has a 2 yr old boy, 4 yr old girl & a cat. The reason we chose a beagle is because we read how great they were with children. The size and temperment seemed appropriate and without much knowledge regarding training we brought our 10 week old pup home.
I have done extensive reading on beagle behaviors & studied training guides & applied the techniques as good as possible. Our dog is 4 months soon and his behavior is too much to handle. He is aggressive with items he finds on the ground, anytime you go to pick something up he runs for it & tries to snatch it quickly, he doesn't like to give ANYTHING back, he jumps on the kids & bites them all over their bodies & when I try & stop him he barks & challenges me.
I have flipped him into a submissive position & once he's calm I let him go then he tries to attack me. I have chased & growled at him & he changes his behavior immediately but returns back to his bad attitude again. I feel like he will never be good with the kids? When I let him out of the crate to play with them it's short lived cause he runs up, jumps & nips at their faces then challenges me all over again. I'm not enjoying his presence. Just when I feel he's settled he flips on me again? When the kids are in bed he behaves 80% better but when they are around he's terrible. I'm holding onto hope he'll grow out of it with constant enforcement from me but I'm honestly not seeing any improvement & my kids safety is my #1 concern.
Please help...

Answer
Hi, I have answered this a couple times and then it keeps getting eaten by my computer  :( I would like to know if you can email me directly and I will answer. I don't know what is happening but I cannot retype all of it again as it has been very long each time and then gone. My direct email is Have4paws@verizon.net. Just identify yourself as Sid and I will answer, ok?