Please explain the "blind yardstick converging-hands balance" trick

I remember when I was in about 6th grade, my science teacher demonstrated how if you begin by holding up a yardstick on its ends with ‘karate-chop’ position hands, you can close your eyes and slowly converge your two hands, ending in a clap position, and the yardstick will always be perfectly balanced. During the process it is almost magical how the two hands take turns, as one always slides while the other remains stationary with respect to the yardstick.

The teacher said this was a result of our great sense of balance, operating unconsciously. Is that correct, or is the explanation more along the lines of the physics of weight distribution?

I have no idea what you are trying to convey:

“…holding up a yardstick on its ends…”

Huh?

Also:

“…with ‘karate-chop’ position hands, you can close your eyes and slowly converge your two hands, ending in a clap position.”

Huh?

How can a yardstick stand on its ends with your karate chop hand and then have them converge/clap.

Also:

“…is almost magical how the two hands take turns, as one always slides while the other remains stationary with respect to the yardstick.”

Huh?

I guess you’ve never done this yourself.

You take a fairly long, uniform object of non-negligible weight and rest each end on top of one of your index fingers, palms inward. You then bring your hands together slowly. You will generally end up bringing them together such that the object remains balanced so long as you don’t force one to move too strongly.

If you hold one hand absolutely still and try to only move the other, the object will put so much weight (and thereby increasing friction) on the other hand that the object will be pushed by your movement instead of staying relatively still as your hands move. It’s certainly possible to move your hands fast enough so that this doesn’t happen, but doing it slow enough with a generic object that creates a decent amount of friction generally will work. As long as the amount of force you’re pushing your hands together with is low enough, it will not be enough to overcome the friction generated when enough of the weight of the object is on one hand.

I understand what he was saying just fine. Hold your arms straight out, hands flat, presumably with the palms down. Close your eyes. Have someone lay a yardstick on your two hands. Slowly bring your hands together. The yardstick will remain balanced as you do so.

I haven’t tried this myself, but it sounds like it’s nothing more than what you would expect from weight distribution. As you bring your hands together the skin on each hand is going to alternate between sliding and sticking to the yardstick. If one hand is closer to the center of the yardstick, it’ll have more weight on it, and therefore be more likely to stick than slip. You’d expect the yardstick to stay balanced across the two hands, with no active balancing required on your part whatsoever.

No you don’t understand. The palms face each other - not the ground.

I used to that all the time as a kid.

The explanation is simple. As soon as one hand gets too close to the center of gravity, friction increases on that side so that it can no longer move until the other hand moves enough to rebalance things.

It’s the latter. It has nothing to do with you sense of balance or any other human or mind quality. You can verify this for example, buy resting the yardstick on pencils held by two different people who slowly move the pencils together with their eyes closed.