First of all, good for you for rescuing instead of buying your dog! You saved more than one life, because not only did you rescue your dog, but you opened up space in a shelter for another dog to look for a home as well. Fixing him is just one more step in the right direction (and may help with his energy levels - it depends on the dog).
I agree with what most people said about training. The woman who suggested that you don't need training (after all you raised kids) is full of it. I have been working in animal rescue for over 10 years, I have been fostering dogs for the last 3 years, and I've had dogs all my life. I still go to training seminars with my dogs regularly, and would seek help with a problem in a heartbeat. When in doubt, I ALWAYS recommend training (if it's a waste of your money, then you're going to the wrong trainer - I still learn new things each time I attend a seminar). Since you have no experience training a dog, training classes will also help you get a feel for the dog's psychological state so that you are better prepared to address any future problems. The worst thing to do with a dog is to get in over your head, and your pup is about to enter adolescence, so now is a great time to make sure you have the basics under control.
Having said that, there are a number of things that you can do on your own while you're waiting for or beginning training. I have 3 dogs at the moment (all of them rescues), and each of them required a different style of training. My65-pound Australian Shepherd is by far the most bumptious, and he was the hardest to train to "stay off." What I found most effective with him was a very simple denial of attention. When he jumps, I turn my back on him, as many times as it takes until he sits and waits. I don't scold him, I don't tell him to get off, I don't make eye contract. I avoid him completely until he sits. Only then does he get any attention. If, when I start to give loving, he jumps, I go back to ignoring him again. It takes a while, but it's a lot more effective than "No" in the long run. After all, he jumps because he wants my attention, to be closer to me, to get me to react to him. Any attention in his case is positive attention, and so that's what I deny him until he is calm. All visitors to my home are instructed to do the same, and if they cannot (children, ignore my instructions, etc.), I crate him while they visit. I rarely have to, because most people don't want a big dog jumping on them, either.
Kids running in a yard are going to be a temptation for your dog, and at this young age, he may not have the self-control to resist. Let him off leash in your yard (assuming your yard is fenced to protect him from traffic and other dogs and to protect you from liability) only when the kids are calm so that you don't encourage bad behaviors. The trainer will help you learn how to work with your dog and rambunctious kids, but that's probably a bit beyond everyone at this stage.
I wish you the best of luck.