What are some children's activies in Port Washington, I have a 5, 8 and a 12 year old?

It depends on your child's interests. There are 2 dance studios in town offering various kinds of dance lessons, the Port Washington Library has an excellent childrens library with activities including crafts and movies. For sports there is the PYA offering basketball, softball, baseball, lacrosse and the PW Soccer Club. There is also a craft studio on Main Street called Soul Shine which offers lots of fun crafts and art. The PW Tennis Academy is the place to go for tennis. There is also North Shore Gymnastics and The Little Gym and various places for martial arts lessons. The PW Childrens Center on located on Main Street is also another great resource. There may be more but this is what came to mind at the moment. I hope this helps.