Lesson Plan

• State the audible frequency range for humans (20 Hz – 20 kHz).
• Explain the physiological reasons the ear is limited to this range.
• Distinguish between audible, infrasonic, and ultrasonic frequencies and give everyday examples.
• Relate frequency to pitch and describe how it is measured.
• Interpret a frequency‑source table and identify which sounds fall in each range.

• Projector and screen
• Speaker with tone‑generator software
• 440 Hz tuning fork
• Handout containing the audible‑range table
• Worksheet for pair activity
• Audio clips of low‑frequency rumble and high‑frequency chirp

Play a deep rumble followed by a high‑pitched chirp and ask students what they notice. Link this to their prior knowledge of sound waves and pitch. Explain that by the end of the lesson they will be able to state the human audible range and justify why it is limited.

1. Do‑Now (5') – Students list everyday sounds they hear and predict whether each is low, medium, or high pitch.
2. Mini‑lecture (10') – Define sound, frequency, pitch, amplitude; present the 20 Hz – 20 kHz audible range.
3. Demonstration (8') – Use the tone generator and tuning fork to show frequencies inside and outside the audible range.
4. Table analysis activity (7') – In pairs, students complete a table matching frequency ranges to common sources.
5. Concept check (5') – Quick Kahoot quiz on why very low or very high frequencies are not heard.
6. Summary discussion (5') – Review key points and clarify misconceptions.

Summarise that humans hear sounds between 20 Hz and 20 kHz, with frequency determining pitch and physiological limits setting the range. For the exit ticket, students write the audible range and one reason it is limited. Homework: research an everyday use of ultrasound and prepare a short description.