Use two, identical glass soft drink bottles as resonance tubes to explore resonance. Hold a bottle vertically, placing the opening near your ear. Ask a friend to stand two feet away from you and blow across the top of the other bottle until a sound is produced. Your bottle will vibrate at the same frequency and be in resonance with the other bottle, but produce a weaker sound.
You’ll need a small, open can, a large, open can, a small conch shell and a large conch shell. Put the open end of the small can next to your ear and listen to the sound. Replace the small can with the large can and listen. Repeat with the small and large shells. Vary the locations where you listen to the sound. The sounds from the small can and small shell are higher in pitch than those from the large can and large shell. The frequency of the sound varies according to the shape, size and type of material of which the tube is made.
Remove the ends from three 19-ounce cans and tape them together in a tube. Hold the tube upright in a flat-bottom container of water. Strike an A tuning fork and hold it horizontally over the resonance tube. Keeping the tuning fork over the resonance tube, move them slowly up and down, while maintaining contact with the water, until the tuning fork sounds loudest. The tuning fork caused vibrations in the resonance tube’s air column. When the air column and tuning fork have resonance, vibrating at the same frequency, the sound of the tuning fork is louder.
Boomwhackers is a set of eight open resonance tubes. Each tube is a different length, made to resonate at the frequencies of the C major scale. When a tube is “whacked,” it resonates at a particular frequency and amplifies it. A tube can be capped at one end to produce a frequency one octave lower than the open tube. You can play simple tunes, such as "Twinkle, Twinkle Little Star," in the key of C major using the Boomwhackers.