You can take the girl out of Montessori, but...
Actually, I don't remember if Will learned how to polish with lemon juice and salt from Montessori or from me, but either way it's such a Montessori-style activity that whenever she sets it out for herself, it reminds me of her preschool afternoons spent at our local Montessori school, rolling out work rugs and carrying activities on trays and sitting on the ellipse to sing the friendship song.
Tangentially, if you're ever looking for a preschool, but have the long-term goal (or even just the possibility) of homeschooling, then I can't recommend a Montessori preschool highly enough. Montessori children are encouraged to be so independent, and so focused in their work for long periods, that they're practically tailor-made for homeschooling.
Anyway, sometimes of a morning Willow will decide that my teapot is looking especially grungy (In my opinion, it's ALWAYS looking especially grungy, but I also never polish it, myself, so I don't have much room to criticize). When that happens, she'll take it to the table, then set out for herself a little dish of salt that she gets from the cabinet and a little dish of lemon juice that she gets from the refrigerator, and a dish towel.
She wraps a couple of fingers in the dish towel, then dunks them first in the lemon juice, and then in the salt.
And then she rubs away the grime!
You can see EXACTLY where she's polished, on account of my teapot is otherwise so grimy.
Polishing with lemon juice and salt takes surprisingly little brute force, although you do build up your muscles through that repetitive motion. I'm especially happy when Will chooses to polish something, because she's still such a reluctant writer that I know that any extra bit of muscle-building in her hands and arms can only help.
And no, she never polishes the entire teapot! Whenever she's done, I remind her to wipe down the teapot with a wet dish cloth to rinse it, and then she puts away her supplies and runs off to do something else.
And then I'll just put the teapot back on the stove top with the clean spot facing out.
Such an improvement!