Here's what I mean by 'foolproofing'. The keyblock has no wide open spaces into which the baren can 'fall' while printing; the kids simply rub almost at random around the block and the lines will print clearly. For the colours too, there were no difficult places.

I also got a bit more sophisticated with the colour layout. This print has six colours, but is done with only four blocks. There is no 'brown' block, as that colour comes from a combination of the yellow and the skin, and there is no 'green' block, as that comes from the yellow and the blue.

When they turned the paper over after doing the blue, and saw the wide green area that had appeared, they always gasped in surprise ...

(click image for a larger version in a 'popup' window)

The image is from the famous 'Inch-high Samurai' folk tale ...