Niall, who should know, says Squeakland is “incredible”. I haven’t tried it myself, but it’s described as “media authoring tool” and is available for Windows, Mac OS, Linux and Unix! Check the “What is Squek?” page for more.
30 years ago this was a fantasy about how children would learn science and math some day on their own notebook personal “Dynabooks”. After many years of building and testing these ideas, today this scenario is real.