Improvisation should occur often throughout development. Improvisation should be spontaneous, not formalized, refined, or repeated. At a beginning level, it should allow children to play with sounds and with musical syntax. National Standard 3 is dedicated to improvisation and should ideally be included in every class.
There are two types of improvisation: free and structured. Free improvisation encourages children to experiment with the sounds of different instruments or their voices. It goes beyond exploration because they are actually improvising a piece from beginning to end. They are making clear music, not just exploring sounds.
Structured improvisation involves prompting the students in some way. There are many different ways of doing structured improvisation.
Orff-Schulwerk, Kodaly, and Dalcroze all have different methods of improvisation. With Orff-Schulwerk, the children might improvise in an ABA ternary form. They would listen to the A section, then improvise a B section. They could be asked to invent a melody on a C major scale using a xylophone or another orff instrument. For Kodaly, children will first invent a steady four beat rhythm either by clapping or singing syllables like sol, mi, and la. Once they build an internal collections of rhythm and pitch patterns, they can improvise a longer pitch or rhythm pattern over it. Dalcroze is similar to Orff-Schulwerk in the way that they listen to something, then improvise a continuation to it. In this case, the teacher improvises on the piano, then the children are expected to improvise with the same style. They can respond rhythmically, with drums or movement, or with pitch, using the piano or voice. Kodaly differs from Orff-Schulwerk and Dalcroze a bit because the students are creating from scratch, versus building from a model.