Skip to main content

Motion (What Unschoolers Do Intead of School)

Three year-old No. Three loves motion.  My walks with her through the neighborhood and around town are always spiked with Three’s discovery of new objects and her new uses for them.  Three was the first to discover that bicycle racks in our town aren’t actually for bicycles, they’re one bar monkey bars, also known as monkey bar.  When she was two, she noticed one day that she could see through to the other side of a bike rack.  Five seconds later, she was holding onto it with two hands, swinging back and forth with her feet lifted off the ground.  One of our fancier neighborhoods who seemed to have figured out this trick, robbed the world of the joy by placing decorative metal work across the opening.  The first time Three found one of these, I realized that two year-olds are capable of looks of the purest, un-mollified disdain. 

It should have been no surprise to me when a few weeks later, Three went from a vertical swing to a horizontal one.  Arriving at the playground one afternoon, I found Three perched on a piece of equipment made for spinning.  We call them—perhaps unoriginally—spinners.   Typically kids stand on it, push themselves off a little bit, pull the leg they pushed with up, and spin for a bit.  It’s a merry-go-round for one.  As I walked over to the bench where my partner was seated, she said, “Watch this,” and nodded at Three.

Three took hold of the handle on top of the spinner with both feet squarely on the ground, not on the little circular platform most kids stand on to enjoy the spin.  “That’s odd,” I thought. 

Then, she started running in circles as fast as she could with the handle still in her hand.  She was spinning up the platform.  As she hit critical speed, she jumped up, and threw both feet away from the center of the spinner.  With the resulting centripetal force, her body swung out making a horizontal line—from head to toe—parallel with the pavement below.  She was virtually flying.  At one point, she brought her other hand down to the standing platform making a sideways T with her arms and body.

Three continues to find new ways to move every day—much to my partner's chagrin, Three recently discovered she could pull a similar ‘spinner’ trick when buses in town go ‘round corners.)

Her exploration of motion is an innate quality of Three’s.  She has no fear, and surrenders her body to whatever she’s decided to try next.  Thanks to San Francisco’s primo weather, and her free unschooling schedule, she’s outside almost all the time.  New opportunities abound at every step!


Popular posts from this blog

Cool Math Tricks: Deriving the Divergence, (Del or Nabla) into New (Cylindrical) Coordinate Systems

The following is a pretty lengthy procedure, but converting the divergence, (nabla, del) operator between coordinate systems comes up pretty often. While there are tables for converting between common coordinate systems, there seem to be fewer explanations of the procedure for deriving the conversion, so here goes!

What do we actually want?

To convert the Cartesian nabla

to the nabla for another coordinate system, say… cylindrical coordinates.

What we’ll need:

1. The Cartesian Nabla:

2. A set of equations relating the Cartesian coordinates to cylindrical coordinates:

3. A set of equations relating the Cartesian basis vectors to the basis vectors of the new coordinate system:

How to do it:

Use the chain rule for differentiation to convert the derivatives with respect to the Cartesian variables to derivatives with respect to the cylindrical variables.

The chain rule can be used to convert a differential operator in terms of one variable into a series of differential operators in terms of othe…

The Valentine's Day Magnetic Monopole

There's an assymetry to the form of the two Maxwell's equations shown in picture 1.  While the divergence of the electric field is proportional to the electric charge density at a given point, the divergence of the magnetic field is equal to zero.  This is typically explained in the following way.  While we know that electrons, the fundamental electric charge carriers exist, evidence seems to indicate that magnetic monopoles, the particles that would carry magnetic 'charge', either don't exist, or, the energies required to create them are so high that they are exceedingly rare.  That doesn't stop us from looking for them though!

Keeping with the theme of Fairbank[1] and his academic progeny over the semester break, today's post is about the discovery of a magnetic monopole candidate event by one of the Fairbank's graduate students, Blas Cabrera[2].  Cabrera was utilizing a loop type of magnetic monopole detector.  Its operation is in concept very simpl…

The Javascript Google URL Shortener Client API

I was working with the Google API Javascript Client this week to shorten the URLs of Google static maps generated by my ham radio QSL mapper. The client interface provided by Google is very useful. It took me a while to work through some of the less clear documentation, so I thought I'd add a few notes that would have helped me here. First, you only need to authenticate your application to the url shortener application if you want to track statistics on your shortened urls. If you just want the shortened URL, you don't need to worry about this. The worst part for me was that the smaple code only showed how to get a long url from an already shortened rul. If you follow the doucmentaiotn on the insert method, (the method for getting a shortened url from a long one), there is a reference to a rather nebulous Url resource required argument. It's not at all clear how to create one of these in Javascript. The following example code shows how:
var request = gapi.clie…