Changes

== Sugar Digest ==

== Sugar Digest ==

1. Over the weekend, there was a [http://lists.laptop.org/pipermail/olpc-sur/2012-February/009989.html discussion of the Yupana]--the Incan abacus--on the Sur mailing list. I was interested because when I originally wrote the [[Activities/Abacus|Abacus]] acitvity, I did some investigation into the Yupana, but was not able to find any definitive description of how it works. Alan Jhonn Aguiar Schwyn recommended [http://www.que.es/moda/videos/yupana-calculadora-inca-metodo-ensenanza-15039.html], which was helpful. Even more helpful was [http://cursa.ihmc.us/rid=1J2NH8QTM-2912G6-PZ5/Yupana como herramienta pedagogica.pdf], recommended by Fernando Da Rosa.

1. Over the weekend, there was a [http://lists.laptop.org/pipermail/olpc-sur/2012-February/009989.html discussion of the Yupana]--the Incan abacus--on the Sur mailing list. I was interested because when I originally wrote the [[Activities/Abacus|Abacus]] activity, I did some investigation into the Yupana, but was not able to find any definitive description of how it works. Alan Jhonn Aguiar Schwyn recommended [http://www.que.es/moda/videos/yupana-calculadora-inca-metodo-ensenanza-15039.html], which was helpful. Even more helpful was [http://cursa.ihmc.us/rid=1J2NH8QTM-2912G6-PZ5/Yupana como herramienta pedagogica.pdf], recommended by Fernando Da Rosa.

So I wrote the [[Activities/Yupana|Yupana activity]]. The beads are organized in columns, where the units (1s) column is farthest to the right; tens (10s) is second from the right; hundreds (100s) is third from the right, etc. When you click on a dot and it will reverse its state (color), and either add or substract value from that column.

So I wrote the [[Activities/Yupana|Yupana activity]]. The beads are organized in columns, where the units (1s) column is farthest to the right; tens (10s) is second from the right; hundreds (100s) is third from the right, etc. When you click on a dot and it will reverse its state (color), and either add or subtract value from that column.

Digging a bit deeper, I came across [http://www.atlantisbolivia.org/decodingquipumaths.htm], which had alternative interpretations of how the Yupana works. In this version, the base is 20, and rows with multiple dots are counted as 2s.

Digging a bit deeper, I came across [http://www.atlantisbolivia.org/decodingquipumaths.htm], which had alternative interpretations of how the Yupana works. In this version, the base is 20, and rows with multiple dots are counted as 2s.

John Watlington suggested yet another interpretation: x1, x2, x5, and x20.

John Watlington suggested yet another interpretation: x1, x2, x5, and x20.

Finally, I decided that the best thing to do is to challenge the user to come up with their own interpretion.

Finally, I decided that the best thing to do is to challenge the user to come up with their own interpretation.

The [http://activities.sugarlabs.org/en-US/sugar/addon/4533 Yupana activity] is available for download from the Sugar activity portal.

The [http://activities.sugarlabs.org/en-US/sugar/addon/4533 Yupana activity] is available for download from the Sugar activity portal.