[Squeakland] More thoughts - Re: Demoing Etoys to kids
HORonT at Earthlink.net
Mon Aug 13 10:05:47 PDT 2007
What I thought was really cool was the moon to sun.
Since the distance from the coin to the moon was 110 moons. And since from
our perspective the moon almost perfectly occludes the sun, the sun must be
110 suns from the moon. That was just too cool!
> -----Original Message-----
> From: squeakland-bounces at squeakland.org [mailto:squeakland-
> bounces at squeakland.org] On Behalf Of stéphane ducasse
> Sent: Monday, August 13, 2007 8:17 AM
> To: Alan Kay
> Cc: squeakland at squeakland.org
> Subject: Re: [Squeakland] More thoughts - Re: Demoing Etoys to kids
> Ok thanks I missed the distance from the eye :)
> On 12 août 07, at 21:42, Alan Kay wrote:
> > Hi Stephane --
> > At 12:11 PM 8/12/2007, stéphane ducasse wrote:
> >> Hi alan
> >> I always liked the way ancient measured pyramid using the shadow of a
> >> know piece of wood and use Thales theorem.
> >> At least it was a really practical example, I used to teach Thales
> >> beauty.
> > Yes, and it is even simpler for the children to think just in terms
> > of similar triangles.
> >>> For example, if we occlude a quarter with a dime and measure this
> >>> carefully, we see that the distance in diameters has to be the same.
> >>> <dimeQuarter.png>
> >> Now I do not understand the "distance in diameters"
> > Check the picture. If it is 9 dimes from the eye to the dime, it
> > will be 9 quarters from the eye to the quarter. If it is 110
> > quarters from the eye to the quarter that occludes the moon, the
> > moon is 110 moon diameters from earth.
> >> Which
> >>> And if we then occlude the moon with a coin (as Aristarchos of
> >>> Samos indeed did!) we will find that it takes about 110 coin
> >>> diameters, and this means that the moon is 110 moon diameters away
> >>> from us!
> >> How do we get 110?
> > You measure the number of coin diameters from the eye to the
> > location of the coin that occludes the moon.
> > Cheers,
> > Alan
> >>> Children love this (too bad adults don't, or they would know about
> >>> this and teach it to children).
> >> Some do :)
> >> Stef
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