Engelberger Five-Tone Recorder
When small childern sing, they may find tone sequences that denote what is in tecnical terms called pentatonic. Pentatonic means a sequence from 5 pitches in a scale. If you play, for example, only the black keys on the piano, you are using the pentatonic scale.
The typical pentatonic scale is the absence of half steps.
We are used to 7 different pitches (diatonic) and deal with the half steps. If a pentatonic and a diatonic melody are compared in part, the pentatonic melody would be freer and more open where as the diatonic would be more fixed.
The pentatonic melody is so to say in the sky, the cosmos closer than the diatonic scale sequence. This explains why the nature of the pentatonic scale sequences appeals more to small kids than the diatonic major or minor.
Small children are free. That is so to say that they are closer to the sky than adults, who are more fixed than the child. Even the pianos white keys allows the pentatonic to be played. For example when one omits C and F, playing only D, E, G, A, and B. Exactly these pitches are what Rudolf Steiner recommends for small children.