### Find Out For Yourself

Investigate sounds produced by lengths of the ruler that correspond to a number pattern.
Take your book and rulers and make one ruler vibrate at lengths of 10 centimeters (cm), 15 cm, 20 cm, and 25 cm. Then try 8 cm, 12 cm, 16 cm, and 20 cm.
Continue exploring until you find four lengths at which you hear at lest four different sounds, or pitches, distinctly. How would you describe these four pitches?
Now use both rulers. Hold them down firmly with a heavy book. Make different lengths extend over the edge of the table and pluck one right after the other. Can you hear and see a difference? If you have a partner, take turns so both of you can look and listen.
If you can, work with a friend, parent or other students using four rulers. Arrange the rulers in sequence--10 cm, 15 cm, 20 cm, and 25 cm-- and pluck them quickly, one after the other. Try this in both ascending and descending order. What do you hear?
How would you summarize what you now know about sound?
IDEAS TO EXPLORE
Play a guessing game with a partner. Pluck the ruler while your partner looks the other way and predicts the length of the ruler. Then switch roles.
See if you can play a tune with ruler lengths. Start with the one below.
Song: 14 14 10 10 9 9 10 11 11 12 12 13 13 14 (cm)
Did you recognize the tune?

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