I'm not a dog trainer or behavior expert, but I read about some simple tests designed by experts that can be performed to determine how safe a dog will be to own. They have never failed me.
1. Put the dog on his back. Put your hand on his chest & gently hold him down. If he immediately starts struggling to get up, he's aggressive & not a good choice around children.
2. Gently squeeze his paws. Dogs' paws are very sensitive to pain. If he reacts by biting, he's not a good choice. He probably won't bite hard, but if he uses his teeth to voice his disapproval, that's not a good sign.
3. Put some food in his food bowl. While he's eating, slowly take it away. If he growls or looks threatening, he's not a good choice. These are things kids may do.
Every dog I've adopted passed these tests & I never had a problem leaving kids along with them.