So today I was showing my students a video about submarines, which showed sailors working on a US Navy Submarine. Part way through the video one of the girls blurted out:

"Why are they all boys?"

So after the video I talked a bit about how if the sub were Canadian, there would have been women onboard, but the US Navy doesn't allow women on Subs. The kids didnt have much to say about it but I thought it was a very insightful comment for a 7 year old.