I am the parent of three boys and my boys had a great time building and flying their Estes rockets. These model rockets have been around for quite a while. I'm not sure how long, but my oldest son was flying them about twenty-five years ago.
The beginner kits contain easy to assemble rocket parts to be glued together and assembled for lift off. More experienced builders, and older kids may want to try a more involved model. Other items will be needed, such as the launch pad and engines. The only other necessary thing to have would be lots of wide open space.
The rockets themselves can be inexpensive or more expensive and have varying characteristics but the idea is to have fun and my boys spent a lot of fun hours watching their Estes rockets fly. Of course finding them once they land is always fun too.