Have a look at the length of the string, and discus the effect on its pitch Ask students to predict whether longer strings will create lower-pitched sounds or vice versa. Here is an interesting question to discuss with your students: Why do we use the word “high” to describe pitches of a higher frequency, when it has nothing to do with the height away from the ground?
Why do you think harp makers placed the shorter strings closer to the player and not the other way around?
Have a look at this idea you can use to demonstrate the workings of the harps pedals.
Background information: The double-action pedal harp has seven pedals. What happens is each pedal changes all the strings of one note name. Each pedal has three positions: top (flattens pitches by a semitone), middle (no change), and bottom (raises pitches by a semitone).There are three positions for each pedal: In the top position it lowers the pitch by a semitone, in the middle there is no change, and in the bottom it raises the pitch be a semitone. If all the pedals are in their centre position, the harp plays a C major scale
Procedure: On the whiteboard, draw seven pedals laid out from left to right (simple ovals or rectangles will do), and label them with the note names from C to B. You can then have the students follow along the whiteboard while you play the C major scale on a keyboard instrument. You can then play the scale again, and alter one note by either a semitone up or down. Ask the students which note was altereed, and in what direction it needs to be moved. You can then have one student run out the pedal in question and draw it again in the position you played. You could repeat this as many times as you wanted for a fun game. For a greater challenge, alter two or more notes.
If you have access to an electric guitar and an acoustic guitar, you can easily demonstrate the need for a resonator, both on the guitar on the harp. The electric guitar uses electric amplification instead of a resonator, but if the instrument is unplugged, it produces only a very faint sound. However an acoustic guitar is easy to hear because the body of the guitar is its resonator, amplifying the sound. The harp also would be far to quiet to hear without a resonator, so you can point it out to the students and demonstrate its function.