Have a look at the length of the string, and discus the effect on its pitch Have the students guess if longer or shorter strings will produce higher or lower sounds. 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.
A modern 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. With all the pedals in the middle position, the harp plays a C major scale.
Draw up on the whiteboard seven pedals (represent them as simple ovals or rectangles), and name them from C to B. Play the C major scale on a piano or other instrument while students follow the pedals on the whiteboard. 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. Repeat as desired with different notes altered. For a greater challenge, alter two or more notes.
You can demonstrate the need for a resonator quite easily if you have acces to both an electric and acoustic guitar. The electric guitar only uses electrical amplification instead of a resonator, so it produces only a faint sound if it is not plugged in. By contrast, an acoustic guitar is readily audible because the guitar body acts as a resonator. Similarly, the harp would be too faint to hear without a resonator, but with a resonator it projects a clear, pleasing sound.
These are just a few simple ideas for writing music lesson plans about the Harp.