ScaleDial: A Novel Tangible Device for Teaching Musical Scales and Triads Harmonic foundations are an important basis for pupils music interest at a young age, however, it is often considered as a non interactive subject matter that requires huge efforts to understand. Typical learning objectives include scale and pitch classes as well as triads and intervals. With our ScaleDial approach, we want to make use of music geometry to provide interactive, graspable, and playful learning experiences. Therefore, we introduced a scale cylinder, a scale cap and four triad tokens to support the exploration of the chromatic scale, an understanding of pitch constellations, and the construction of triads. In the following, we will describe each part in more detail. The chromatic scale is an important basis for music. For our approach, we use the circle visualization of the chromatic scale to build an interactive scale cylinder. The pupil can touch every note. The respective note name lights up and the corresponding sound is played. Further, key signatures like major or minor keys play an important role. Therefore, we build on the circle pitch constellation and derive a physical major scale cap that can be stacked on the chromatic cylinder. The cap physically covers all notes outside the major scale with extruded circular segments and can be rotated in twelve discrete positions. Every position represents a key signature in which the respective notes or even notes outside the scale can be played by touch. After key signature has changed an animation plays a whole scale starting from the currently selected note. Finally, our approach supports the exploration of triads. We looked at the four triad types, draw the pitch constellation in a chromatic circle, derive triangles and finally manufacture wooden triad tokens. In summary, we have a major triad, a diminished triad and an augmented triad. Every triad token can be placed on top of our chromatic cylinder and rotated at twelve discrete positions. If a token snaps to a new position the triad sound is played and the respective note names light up. Further information about the construction of the triad is engraved in the wood. A pupil can experiment and compare different types and get direct visual and auditory feedback. The following short sequence shows how a pupil try out different notes, major scales, and triads. As a last point, we want to show technical details of our tangible device. As you can see in the pictures, our ScaleDial device consists of several LEDs, switches, integrated circuits, reed contacts and content masks. The triad tokens are fabricated with a laser cutter and are made of wood and magnets. If a magnetic triad token moves above a reed contact our system recognizes its position. To sense touch input, we use copper tape and capacitive sensing. Finally our scale caps are 3D-printed. Further technical details can be found on our project website. ScaleDial: A Novel Tangible Device for Teaching Musical Scales and Triads.