Fifty years of memories meant a lot of reminiscing when a group of PS 1 retirees recently gathered to celebrate. They met in 1968, the year they started their teaching careers at the school in Sunset Park, Brooklyn, and they get together every few months to recall shared memories and to celebrate weddings, births and birthdays. But the Dec. 2 gathering was special because it marked half a century of camaraderie. During that time, some group members became deans or chapter leaders or, in the case of two — Joanna Scarpa and Frank DiPiazza — principals before retiring. But through the years, the common denominator has always been friendship. The retirees helped May Stein, a former chapter leader, celebrate her 100th birthday in November. And at the afternoon celebration on Dec. 2, held at the Brooklyn home of Lilianna Reichert, they waxed nostalgic, reminding each other of the days when men had to wear jackets while teaching and women had to wear dresses and, even on the hottest days, were not allowed to wear sandals. Cliff Popel, who served as chapter leader for 20 of his 35 years at PS 1, remembers how “we bonded professionally, seeking justice, to oust a horrible principal when I realized I couldn’t fight the battle alone.” Retired District 15 Representative Bob Zuckerberg worked so closely with the PS 1 staff members that they welcomed him into their group. “Over the years, I saw the chapter come together in unity and strength and mutual respect,” he said, while also seeing “friendships grow.”