When I first started teaching I had a laser disc that was my prize possession. Anything I wanted to show my students was on it. My favorite set of videos was the odd reproduction set. Gastric brooding frogs, mouth brooding fish, the frog that broods the eggs/tadpoles on its back, etc. I wish I still had that disc or could remember the name of it.
In defense of the fourth grader who asked what end the egg comes out, they don't know anything about reproduction unless they have been around animals. Real sex ed is extinct from schools and will remain that way until either common core and high stakes testing is gone or decides to test it. Fourth graders are what, 9 years old? They don't have much "common sense at that age" and none of the life experiences we have.
Today we were egg selling and I had one dozen that nobody seemed to want b/c it had a white egg from my Lakenvelder in it. The comments were mostly along the lines of, "I want country eggs." "I don't want store bought eggs." I guess white eggs only come from commercial chickens????? No problems though, the white egg has a date with some buttermilk pancake batter in the morning.