Today my class did a lab exercise to learn about probabilities and genetics. Part of the lab activity told them to tape a few colored disks together to simulate the way gametes fuse during fertilization. I brought tape with me to class, but forgot to put it out for the students to use. It wasn't really necessary, and most of the students finished the exercise without it, but one girl really started complaining about my "lack of preparedness."
Her: How are we supposed to finish this if you didn't even bring tape?
Me: I brought tape. It's in my bag. You don't really need it, but I'll go get you some if you want.
Her: I do.
I went and got a roll of tape out of my bag, and tossed it to her lab partner.
Me: Here you go. And while you're at it, why don't you go ahead and use that to tape her mouth shut too?