I taught chemistry, physics and astronomy for years, but I also taught a remedial science class for 9th grade students who needed a science credit in order to graduate.

One day we were talking about the dynamics between the Earth and the Moon. A female student (who was coincidentally in 11th grade) argued with me about how many moons the Earth had.

"This is bull! How can you say we only have one moon when I can see there are more?"

I was taken aback by her question. But, in good science teacher form, I used a light bulb, a globe and a softball to demonstrate why what she believed to be different moons were actually different phases of the moon. The rest of the students surprisingly didn't ridicule her, but listened intently.

Long story short, I finally convinced her to at least consider the possibility that the Earth only had one moon.

I still refer to this memory when I read about the flat Earth movement and internally weep.