People generally understand what sexism and racism mean, but they struggle to grasp “ableism,” special education teacher David Friedman told attendees at a “Demystifying Disability” workshop on Dec. 3. About 25 school staff gathered for the session, co-sponsored by the UFT, at the union’s Queens borough office on International Day of Persons with Disabilities. Friedman, a kindergarten teacher at PS 69 in Jackson Heights, based it on a three-part workshop he developed at his school after experiencing disability-based discrimination. “I wanted to turn a negative into a positive,” he said. He collaborated with disability activist Emily Ladau, author of “Demystifying Disability: What to Know, What to Say and How to be an Ally.” Friedman has had a multiple sclerosis-like immune disorder for 24 years and has used a wheelchair for about 12 years. After the workshop was well-received at his school, Friedman contacted his superintendent and the Queens North director of special education about reaching more people. That outreach led to the Dec. 3 workshop, which also included a presentation from INCLUDEnyc on the history of disabilities and disability rights and another on software with accessibility features.