It's hard to remember the names of all of them. Girl Guides were largely U.C. The various parts of the scouting movement were non-denomimational though many troops, etc. having a church meeting place were denominational in membership. Anglicans had Boys' Brigade. Baptists and Presbyterians also had their own youth groups - almost all divided on gender lines. Jews had groups sponsored by B'nai Brith, most of them excellent. But they, like the others, began to wither due to lack of leaders and members in the 1960s. Unfortunately, that gave the Israeli lobby a chance to take over B'Nai Brith and use it as a propaganda agency for the Israeli government.
Boxing clubs were very, very popular, especially in poor and/or violent districts For many, it was the only chance, if a slim one, to escape a life of poverty. It was also useful to help survival in the community. They've now almost disappeared.
For those, like scouts, which had junior and senior sections, the dividing line was usually age 12. That was because, to that age, they were as pure as Adam and Eve on the first day. Then they became sexual, and potential beasts. Thus the separation of elementary and high schools. As well, high schools often used to separate boys and girls in different classes and, sometime, ini different buildings. All of these movements were born out of a Victorian age reacting to a world of violence, sexual abuse, sexual perversion, massive prostitution - and so obsessed with the purity of early childhood. That's why Lewis Carroll had picnics and took nude photos of little girls - but usually abandoned them once they reached eleven or twelve. And that is why it was so important that Peter Pan should never grow up. He had to be forever a child, and without sexuality.