There are twenty-six bones in each of your feet and thirty-three joints, and for most of your life they have been inside a stiff box with a raised heel, doing approximately none of that.
Why a teacher keeps talking about them
Because everything above them is being organised on top of whatever they are doing, and I can see it from the front of the room.
If your weight sits on the outside edge, your knee tracks accordingly, your hip compensates, and your lower back sorts out the difference. Correcting the back is treating the last link in that chain.
This is why I spend what must feel like an absurd amount of time on where the ball of your big toe is. It is not fussiness. It is the bottom of the stack.
What has gone wrong for most people
Toes that no longer spread, because they have been held together for decades. An arch that neither lifts nor lowers on demand, because it has never been asked. Ankles that do not move much.
None of that is a defect. It is disuse, and disuse reverses.
What actually helps
Being barefoot, which my class already gives you and which is a large part of the value nobody counts.
Standing positions where you are told to press through specific parts of the foot, and doing it rather than nodding.
Spreading your toes deliberately. It looks ridiculous and it works, and the fact that many people initially cannot move their toes independently at all is the argument for it rather than against.
In this town specifically
You are probably in sandals or barefoot most of the day already, walking on sand and uneven ground, which is doing more for your feet than anything you could buy.
That is one of the quiet advantages of practising here rather than somewhere cold, and it is worth not undoing it with stiff shoes for the sake of a walk into town.
The measure
Can you lift your big toe while the other four stay down, and then the reverse.
Most people cannot do either at first. Both come back within weeks of paying attention, and something in the knee or hip usually gets better while you are not looking.