Intervalletjes

Intervalletjes is a Dutch term that literally means "little intervals" and is commonly used in educational contexts to refer to small intervals in both music and mathematics. The word is the diminutive form of interval and is typically used informally, not as a formal technical category.

In music theory and pedagogy, intervalletjes refer to small musical intervals, usually seconds and thirds, and sometimes fourths. They are employed in ear training and sight-singing exercises to help learners recognize pitch relationships, quality (major, minor, perfect), and simple melodic contours.

In mathematics, intervalletjes are informal terms used in Dutch teaching materials for small subintervals of a real interval. They serve to illustrate ideas such as length, partitioning, and the behavior of functions on restricted domains. Depending on the example, an intervalletje may be open, closed, or half-open (for instance (a,b), [a,b], or [a,b)).

Although common in education, intervalletjes are not a formal mathematical concept and are generally replaced by standard terminology like subintervals in formal texts.