Objective (optics) Puns

Me, talking to my gang of teenage kids about their day. I asked my oldest son what he was working for the upcoming science olympiad. My son: "We're working on a pendulum." Me: "Must be a lot of back and forth." ACTUAL LAUGHTER! After we settled back down, my son said, "We're also working on objects." I said "Objects?" puzzled. "No Dad! Optics!" "Oh! Optics.....I see. (big grin)" Laughter again! TRIUMPH!