OOPs sorry. Having written this I see you mentioned Sniff above and said it wasn’t suitable for your kids.
Do have a look though, because there are very short sample programs detailing how to use each module.
You can use Sniff which is a textual based language very similar to scratch in its commands. Ian Stephenson has developed the interface to Flotilla hub and its modules. I’ve been using it for a couple of weeks now and it is fairly easy to learn and use. See this link http://www.sniff.org.uk/2015/12/sniff-and-flotilla.html
I have been working with Ian testing some of the modules that are not in the current release 24, and I think that all of them are now pretty well complete. He will supply pre-release copies on request. See the discuss section of the Sniff website.
Using them I have written programs to:
control the Flotilla buggy with the joystick.
display lower and uppercase text and numbers on the Matrix.
Control the position of a single lit pixel on the matrix with the joystick
Use the colour module to illuminate the rainbow leds with the colour being observed with a reasonable match when “looking” at red, blue,green, blue and yellow card.
Control Sonic Pi with the touch keypad, also using the slider and dial controls to adjust notes and select the synth used.
display animated patterns on the Matrix and scrolling text messages.
It is very versatlie and far more powerful than using Rockpool.
I’ve tried it with both Pi2 and Mac using the newest version of the firmware in both cases, which allows you to communicate at 115200 instead of 9600 baud.
Today we have finished debugging the number module which will display both integer and real numbers, right justified on the display. (up to 4 digits)