Changes

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.

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 subtract 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, 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.

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

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 Library.

The [http://git.sugarlabs.org/yupana source code] is available on the Sugar Labs Gitorious server.  

The [http://git.sugarlabs.org/yupana source code] is available on the Sugar Labs Gitorious server.