Hello,
I would like to buy a netbook for a jung child (12) for diverse mathematic (kurve representation -typically gnuplot-, probability calculation, etc. ).

Which distro do you recommend?

Debian (Lubuntu..) based or other?

Based on my experience, I would say: lubuntu and install diverse programs like gnuplot etc.
But: another opinion and another recommendation is welcome.

The netbook must not have wlan and GPRB access (internet only via LAN till he is older).
I was thinking about a 2nd hand eeepc or samsung nc10 (model not decided).

Usually I would go for something like Edubuntu in that situation, an Ubuntu version especially for use in schools.
http://www.edubuntu.org/

If you're going to buy a 2nd-hand netbook you need something light. I always recommend using any distro with its default gui: it's the one with the most users and so gets the most attention and quick bug fixes.

One possibility is Fuduntu. Runs in 384MB, rolling-release but not bleeding edge, user-friendly. It has gnuplot.
http://www.fuduntu.org/wiki/index.ph..._in_Repository
http://www.linuxquestions.org/review...page/15/sort/7

Another is Zorin-OS Lite. That recommends a Pentium II and 128MB. There's plenty of software from Ubuntu.
http://www.linuxquestions.org/review...page/15/sort/7

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Lubuntu/Edubuntu is a good choice, Fuduntu is also a good suggestion (it's what I personally run on my EEE 900HA). A case could also be made for something like Debian or Slackware if your son has interest in learning the inner workings.

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