I can’t say for certain which was first. The earliest I can recall specifically in a theater would have been 1973 Disney’s animated Robin Hood. I would have been 6 at the time. Something else may have come sooner. I also remember seeing Frogs at the drive in. That would have been 1972 (age 5). There would have been two movies, the first more suitable for kids (can’t recall now). The plan was, I was to watch the first movie, then lay down and sleep during the second (Frogs). I peeked, and regretted it. Scared the crap out of me. My parents often talk about remembering the dirty looks they got from people for taking me to see Jaws in the theater when I was 8.