Our choice, which indeed goes against several longer standing conventions (like 0=East, +=counterclockwise, or 0 = N to 360 clockwise), was adopted because we were looking for something that would be close to how a 7 year old child thinks and had a symmetric use of positive, negative and 0 (the original Etoys was for a younger age group). This has worked very well and has many merits for all the ages of children we work with.

And, of course one can assign e.g. 245 to heading and the player will point as expected.

I think the preference you suggest would be a good idea. There is already one for all playfields (including the world desktop) as to whether (0,0) should be in the lower left corner or the center of the rectangle ([] origin at center). Both have their merits. Similarly, both negative degrees and staying positive around the circle have their merits. And we should probably (and likely will) put in a preference for the school math system, now that we are starting to work with older children who are somewhat thinking along those lines.

I think starting with other than 0 would be a bad idea (and would also violate the compass convention). Similarly, school math starts with 0 pointing East, not 360.

If you want to see the regular compass headings you can write a simple script that ticks once or twice a second that does the easy conversion into a variable, then you can use a watcher to see the value on the screen.

The debates we have are not about your issue but the more critical one of whether we should have gone with the "school math" conventions for more coherence later on. I still like starting with the compass with N pointing up and clockwise for +. But there is a good QWERTY argument for the school math conventions. (This gets more pernicious with older children who have to learn the school convention -- and when vectors are used -- should they be in school math or in compass?)

Cheers,

Alan

At 03:19 PM 5/25/2007, mstram wrote:

While playing with the Etoys, I've noticed the "weird" heading numbers.

By that I mean when the object's heading passes 180 degrees, instead of continuing on to 190 ... 270 .. 360, we get the negative numbers.

Why was this convention adopted ?

I think if kids ... and some us "older" kids are going to be using headings it would be more educational and instructive to use "real" headings.

Maybe an option / preference could be setup on which heading numbering system to use.

The only minor problem I can see is whether it should be "0" or "360" to begin with.

Just for the fun of it, I'm digging in and seeing if I can construct my own subclass to use the "360" system. I have an idea for an ATC simulation I'd like to do and "real" headings .. or at least converted for input and output would be a must.

Mike

View this message in context: http://www.nabble.com/Weird-Heading-numbers-tf3818581.html#a10811065 Sent from the SqueakLand mailing list archive at Nabble.com.

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Compasses, GPS, Aircraft, Marine Vessels all use "real headings".

I've never heard of any other use for them (before playing with Etoys ;) )

Mike

From: Paulo Drummond ptdrumm@terra.com.br To: mstram mstramba@sympatico.ca CC: squeakland@squeakland.org Subject: Re: [Squeakland] Weird Heading numbers Date: Fri, 25 May 2007 23:50:47 -0300

Imho, there is no such thing as "real headings". Geometry, as its mother Mathematics is a wonderful symbolical language to provide us all means of mapping the physical world as we see it.

The use of semi-circular geometrical convention helps (among other things) in:

1. give the sense of "negative" when the object passes "downward" or "to

the other side" of an 2-D axis (another convention); 2) the coming back rationally to zero instead of jumping from 359º59'59" to it.

cheers, Paulo

On May 25, 2007, at 7:19 PM, mstram wrote:

...

While playing with the Etoys, I've noticed the "weird" heading numbers.

By that I mean when the object's heading passes 180 degrees, instead of continuing on to 190 ... 270 .. 360, we get the negative numbers.

Why was this convention adopted ?

I think if kids ... and some us "older" kids are going to be using headings it would be more educational and instructive to use "real" headings.

Maybe an option / preference could be setup on which heading numbering system to use.

The only minor problem I can see is whether it should be "0" or "360" to begin with.

Just for the fun of it, I'm digging in and seeing if I can construct my own subclass to use the "360" system. I have an idea for an ATC simulation I'd like to do and "real" headings .. or at least converted for input and output would be a must.

Mike

View this message in context: http://www.nabble.com/Weird-Heading- numbers-tf3818581.html#a10811065 Sent from the SqueakLand mailing list archive at Nabble.com.

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From: Paulo Drummond ptdrumm@terra.com.br To: squeakland@squeakland.org, Subject: Re: [Squeakland] Weird Heading numbers Date: Sat, 26 May 2007 01:21:16 -0300

On May 25, 2007, at 11:57 PM, Mike Stramba wrote:

...

Compasses, GPS, Aircraft, Marine Vessels all use "real headings".

Ok. Try explain to a 8-year child that 0 = 360.

You don't need to. There is no such thing as heading "0".

Headings go from 1 to 360.

...

I've never heard of any other use for them (before playing with Etoys ;) )

It's Geometry, in its very roots. I bet starting with this negativity of angles, relativity of things, one who learned with this principles in mind can understand the real basic Geometry (Euclidian, Cartesian, Vector Space etc) much better, much earlier.

We're talking about *headings*, not *angles*. If we're not, then the parameter should be re-named to "angles" :)

Anyway , I didn't realize that the scripts would respond to "190-360" and internally correct / do the right thing. So I just need to figure out the display/script thingy that Alan suggested.

It's also been "awhile" since I've been in school, but I've never heard of East being referred to as 0 degrees !

By the time these kdis are adults, all the planes will be automated anyway ... or all the airlines will have gone bankrupt ;)

Mike

Yes -- thanks Paulo.

Logo uses all child centric references such as right and left with the reference being up = N. One of the experiments early on in Etoys was to see how well + and - could be used in place of right and left with ~ 7 year olds. This was going to be part of a whole vectorized cuisinaire rods approach to numbers (that used some results we got in the Vivarium) that were unified with the number line way of thinking of + and - as directions (also right and left) of one dimensional vectors.

When the Etoys demo started being used in schools (instead of the home as originally planned) we found that grades 4-5-6 were a better fit with the tradeoffs between what children can do and what adults want to learn. So we never carried through the concrete number representations originally planned.

(However, now we are going to because the OLPC XO needs to have a K-12 range. This actually requires a somewhat different approach to Etoys than the demo version we have now, and we are working on it, which supporting current Etoys for the various XO builds.)

Most adult conventions and forms have huge QWERTY components which make learning more difficult for children. However, eventually the conventions need to be added in. It's imperative to start children thinking in the strongest and most intuitive way -- then we can figure out how to merge in the somewhat ad hoc conventions that adults have devised. Various ways of thinking about numbers, lengths, directions, magnitudes etc is a ideal way to eventually get to some of these conventions. But, e.g. trying to get children started into real numeracy with positional notation is really bad, even though it is a mainstream convention ... the general result in America is that children don't get numerate, even though they are forced to learn how to parrot a few of the conventions.

Cheers,

Alan

At 09:21 PM 5/25/2007, Paulo Drummond wrote:

On May 25, 2007, at 11:57 PM, Mike Stramba wrote:

...

Compasses, GPS, Aircraft, Marine Vessels all use "real headings".

Ok. Try explain to a 8-year child that 0 = 360.

...

I've never heard of any other use for them (before playing with Etoys ;) )

It's Geometry, in its very roots. I bet starting with this negativity of angles, relativity of things, one who learned with this principles in mind can understand the real basic Geometry (Euclidian, Cartesian, Vector Space etc) much better, much earlier.

cheers, Paulo

...

Mike

...

From: Paulo Drummond ptdrumm@terra.com.br To: mstram mstramba@sympatico.ca CC: squeakland@squeakland.org Subject: Re: [Squeakland] Weird Heading numbers Date: Fri, 25 May 2007 23:50:47 -0300

Imho, there is no such thing as "real headings". Geometry, as its mother Mathematics is a wonderful symbolical language to provide us all means of mapping the physical world as we see it.

The use of semi-circular geometrical convention helps (among other things) in:

1. give the sense of "negative" when the object passes "downward"

or "to the other side" of an 2-D axis (another convention); 2) the coming back rationally to zero instead of jumping from 359º59'59" to it.

cheers, Paulo

On May 25, 2007, at 7:19 PM, mstram wrote:

...

While playing with the Etoys, I've noticed the "weird" heading numbers.

By that I mean when the object's heading passes 180 degrees, instead of continuing on to 190 ... 270 .. 360, we get the negative numbers.

Why was this convention adopted ?

I think if kids ... and some us "older" kids are going to be using headings it would be more educational and instructive to use "real" headings.

Maybe an option / preference could be setup on which heading numbering system to use.

The only minor problem I can see is whether it should be "0" or "360" to begin with.

Just for the fun of it, I'm digging in and seeing if I can construct my own subclass to use the "360" system. I have an idea for an ATC simulation I'd like to do and "real" headings .. or at least converted for input and output would be a must.

Mike

View this message in context: http://www.nabble.com/Weird- Heading- numbers-tf3818581.html#a10811065 Sent from the SqueakLand mailing list archive at Nabble.com.

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