Hands-on science

Science World, April 26, 2004

Check out these hands-on experiments after you've read "Good Vibrations" (p. 15) and "Paradise Lost" (p. 8). They're fun and foolproof!

FEEL THE RHYTHM

In "Good Vibrations" you learned that elephants communicate by transmitting sound waves through the ground. Discover how sound travels through different mediums.

YOU NEED:

4 pieces of kite string (35 cm, or 14 in., each) * metal hanger * paper * pencil

TO DO:

1. Tie the end of one string to one end of the horizontal part of a metal hanger. Tie a second string to the other end of the horizontal part of the hanger.

2. Wrap the end of one string around an index finger three times. Wrap the second string three times around your other index finger. Make sure both strings are the same length.

3. Hold the strings so the hanger dangles freely in front of you. Gently swing the hanger so it bumps against the side of your desk. Record what you hear (for example loud/soft sound, high/low pitch).

4. Now, place the tip of one index finger into each ear (not too far!) and lean over so the hanger dangles freely. Again, gently swing the hanger so it bumps against the side of your desk. Record what you hear, and what you feel in your ears.

CONCLUSIONS:

Was the sound loudest when your fingertips were in or out of your ears? Which case best describes the way sound reaches an elephant's feet? Explain.

SCHOOL YARD BIODIVERSITY

In "Paradise Lost" you read about the amazing plant and animal diversity found in Borneo's rain forests. Conduct a biodiversity survey in your school yard to see which areas have the greatest variety of life.

YOU NEED:

hula hoop * sheet of poster board * colored markers * small shovel * clipboard and paper (for field notes)

TO DO:

1. As a class, look around the school grounds for three different locations to conduct a biodiversity survey (for example, grassy area near a fence, area with trees, full-shade area, full-sun area, and so on).

2. Divide into groups of three to four students.

3. Choose a study location for your group. More than one group can work in the same area.

4. Place the hula hoop on the ground at your location.

5. Have one student take notes as the other students list the kinds of plants, insects, and other organisms living inside the hula-hoop plot.

6. Dig a hole (8 cm by 8 cm, or 3 in. by 3 in.) in the plot.

7. Look for insects in the soil. Record your findings.

8. Back in the classroom, use the poster board, markers, and field notes to draw the ecosystem your group observed. Display your group's poster and discuss your findings with the class.

CONCLUSIONS:

Which location had the greatest biodiversity? Discuss the possible reasons.

ANSWERS

Feel the Rhythm:

The sound was louder when your fingertips were in your ears. That's because sound waves transmit better through a solid (string) than through a gas (air). How it works: When you tap the hanger, it vibrates. These vibrations--sound waves--travel through the air to your ears. When you place your fingertips in your ears, the sound waves travel from the hanger, up the string and into your ears. This was similar to how sound waves travel to an elephant. That's because the waves traveled through a solid (the string and then your fingertips) rather than through the air.

School Yard Biodiversity:

Answers will vary depending oil locations chosen for the biodiversity study. Look at the number of different kinds of grasses/plants on each poster. Also discuss the variety of animals on the surface and in the soil. Learn more about biodiversity at these two Web sites:

http://research.amnh.org/biodiversity/Index.html?scr=h h

http://www.conbio.org/SCB/Services/Education/faq.cfm