Did you know that you might be able to wipe over your socks or shoes in wudu' instead of washing the whole foot?
If you put the socks/shoes on while you had wudu' in the first place, and if they aren't impure in the first place, and if you haven't been wiping over them for more than a day (or three days if you're traveling), and they aren't so thin that you can see the color of the skin beneath them, and you're supposed to wipe the top, not the bottom.
(If you're not sure about the rulings on wiping over socks, Islamqa.com has plenty of answers about it, if you do a search on "socks." Usually all the fatwas are backed up with proof.)
Now, picture a child, maybe 10-12 years old, making wudu' beside you. The child is wearing flip-flops. Not socks, or shoes, but flip-flops. And when it comes time to wash the feet, the child instead of washing the foot, she just touches the bottom of the flip-flop sole with a finger.
Does that seem like an acceptable way to make wudu'? I didn't think so.
So I mentioned this to her, explaining that she should wash her feet. And she countered by saying that it was permissible to wipe over shoes and socks which is what she was doing. So I replied that it is permissible of course to wipe over socks or shoes if one has wudu' but she wasn't wearing socks or shoes, she was wearing flip-flops that completely exposed her foot, so she couldn't just wipe her flip-flop sole to avoid the laborious process of wiping her feet.
Anyway, the whole event kind of made me wonder who taught her how to make wudu' in the first place, and why she thought that it would be okay to tap the back of her flip-flop. She had learned that it was permissible to wipe over the socks, but hadn't learned the rulings about it to apply them properly.
I wonder how many of us have this problem--that we've only learned something partially and so we implement it incorrectly? This is why it is important to study our deen, even if we think we know it, even if we think we learned it as children. We might be making little mistakes that go unnoticed.
And I'll recommend islamqa.com if anyone has questions about rulings on wiping over the socks.