Kolibrios – One of smallest OS
This is one of smallest OS over the world and you can use it for learning basics of computer to your children or students.
This OS needs to 8 MB RAM and it’s very very small but has most abilities of a modern OS. Also it has a friendly GUI and has some useful applications such as viewers and editors. This OS supports read and write on FAT/FAT16/FAT32 and read NTFS partitions.
You can download live and installable image for this link: http://kolibrios.org/en/download
See some screen-shots from this OS: