Leap of Leaps is a level 4 piece using rolled chords, harmonics, and pizzicato. Model these skills to the students and practice each of them as separate activities.
For harmonics- many students find it easier to produce a clear sound by playing closer to the bridge (ponticello). Make sure they understand to gently remove fingers from the strings after playing to allow the resonance to ring out.
For rolled chords- show students how to “drag” p across the strings, creating a controlled, staggered sound. Ask students to listen for timing and articulation, striving for a uniform sound within the group. You may ask small groups to play while others listen. Listeners provide constructive criticism about timing, tone, etc. Ask specific questions like “Did the players roll each note at the same speed?”
For pizzicato (aka palm muting)- model a clear pizz. sound. Show the students how it is easily possible to use too much flesh on the string, dampening the sound more than desired. With the proper technique, they will create a percussive attack and maintain some resonance. Experiment with very short articulations as well, deciding on the uniform sound you want.