Katherine G. Harris said (stuff deleted) > I firmly believe that children >must be able to manipulate fractions in order to progress >beyond whole number arithmetic! (more stuff deleted including interesting observations and questions)
I want to challenge your belief. In France, students do not manipulate fractions until around 7th or 8th grade. Prior to that they do a lot of work with fractional quantities using decimals connected to measurements.
In the 2nd International Mathematics Study, all US and French teachers reported that their students had had the opportunity to learn 2/5 + 3/8 during the 8th. At the beginning of the 8th grade, 42% of US students and 5% of French students were able to select the correct answer to this problem from five alternatives. At the end of the 8th grade, 59% of US students and 73% of French students got it right.
I think students can and do progress beyond whole number arithmetic independent of fraction manipulation. I think the algorithms are complicated and difficult to remember for many students. We teach them, they forget them, we teach them again, they forget them, again,... . Learning fractional arithmetic, I believe, is helped by maturity and intensive study. Certainly, if the US adopted the metric system, we could delay covering fractions as the French do. Regardless, I think it might be better instructionally to stress fraction concepts in elementary grades, stress decimal arithmetic next, and save fraction manipulation to later grades.
I'll try to respond to your technology question later.