This is the time of year we see dogs and puppies chasing skateboards, rollerblades, bicycles and barking at kids playing basketball in their driveways.
If you live in a neighbourhood with lots of children, ask them if they would be willing to help you train your puppy or dog to be comfortable around skateboards, bouncing basketballs, rollerblades etc. Prep yummy treats for both the dog and the kids and spend a few moments rewarding your dog for calm behaviour. Make sure you start off with the least intense version of activity. Gradually work up to more movement.
For example: kids standing still and bounce the ball - once or twice. Increase the number of bounces gradually. Then have the kids bounce to each other - once. Gradually add all the elements of a basketball game - more movement, more bouncing, tossing the ball, etc. Don't forget to include teaching the dog that sounds of children (yelling, etc. are good too!)
If at any point the dog/puppy gets over excited, slow down the progression. Small training sessions are better then long ones.
Find the spot on the leash where when you step on it, the dog has enough leash to sit comfortably. Put a knot at that spot so you can find it quickly when you need it. When you stop walking, step on that spot. This prevents the Opposition Reflex  (you pull one way, the dog pulls harder the opposite way) from kicking in as you are not pulling back on the leash and the dog is unable to lunge forward.
On walks, when you don't have any control over moving objects
1) make sure you keep yummy treats in your pocket
2) the moment your dog notices the movement, stop walking and begin treating.
3) or, keep walking but treat as you walk past
 If necessary, cross the street, or give a wide berth so you create more distance and it will be easier for your dog to settle.