they think happens to the air particles around the rubber band. The
text then provides follow-up questions like “Do air molecules and
sound travel the same distance?” and “What does the frequency tell
you about the pitch of a sound?” For each question, experiments are
conducted by the students. They need to think about logical answers
to small-step-formulated questions about their observations.
2. How do we hear?
At station 2, students read about the anatomy of the outer and middle ear and what happens when sound arrives there (Figure 2). The
information of the sound wave is transmitted to movement of the
eardrum. Through the lever system of the ossicles and transmission
to a smaller surface, the oval window, the force of the vibration is
increased before it enters the inner ear. Students conduct experiments about the lever amplification of the ossicles and about force
3. How do we distinguish frequencies?
At station 3, students learn about resonance and eigenfrequency of
objects (Figure 3). Students conduct experiments with two tuning
forks: when the first is hit, the second will resonate only under certain circumstances. This is the only experiment that all the student
groups need to do either one after the other or together, because of
the silence needed and the relatively high cost of the tuning forks.
It is possible to use another room for this experiment to obtain a
silent environment. Understanding resonance and eigenfrequency
is important in learning about how the cochlea in the inner ear
functions. Students read about its anatomy and work with a model
of the basilar membrane, represented by a metallophone, to understand how the basilar membrane works.
4. The limits of hearing
At station 4, the natural limits of human hearing are introduced
(Figure 4). Ultrasound and infrasound are described. Students
explore the reasons for these phenomena by analyzing the metallophone as a model of the cochlea. Afterwards, hearing loss caused
by very loud sounds is introduced, and possibilities for protecting
one’s hearing are given.
Alignment with NGSS
This intervention is designed for students in middle school, about
15 years old. It addresses several core ideas of the NGSS (Achieve,
2013). It best fits Physical Science with its performance expectations
but also fits Life Science. The hearing module enables students
to develop usable knowledge to explain real-world phenomena in
physics and biology. It covers the performance expectations of
several scientific practices. For example, students use models and
Figure 1. Experiments at station 1 (left to right): sound creation—rubber band guitar; sound travel—marked spiral in motion;
sound properties—frequency and amplitude.
Figure 2. Experiment at station 2: the lever system of the ossicles.