Back a long time before political correctness existed, but when people (in public) were more polite, my grade school taught the way to remember key names for the sharped keys as:

"Go Down And Eat Breakfast."

And on the same "theme," the keys with flats in them were:

"Fat Boys Eat Apple Dumplings."

Some of the kids seemed to be able to remember other phrases for either the sharps or flats, but not both directions at the same time. "Attaching" both to the same idea of "eating" got most of them to the point of remembering them both (at least 'till the afternoon bell rang and they went home and washed their brains).

Of course the order is reversed when you increase the number of flats, from the order as you add sharps, but with the "neutral" key of C in between, flipping either one lets you remember the entire circle of fifths (which was an advanced subject not discussed until fifth grade, IIRC).

Some of the other phrases are rather cute, but this pair should be generally acceptable for teaching to young children, even in "formal" contexts - although political correctness by now may have made it - or soon will make it - impolite to refer to "fat boys" in any context. Maybe you could substitue "fluffy" for "fat," like several of my acquaintances do(?).

John