The Caliper
A Publication for Users of Vernier Products

Real Kids - Real Scientists

Dragonflytv, a PBS science show featuring real kids doing real science, used Vernier sensors in two featured investigations during their last season of broadcasts. They did one feature on the overnight temperature inside a snow shelter, and another in which they investigated whether prairie dogs make different barks when presented with different visual threats.

Have you ever wondered, "How warm can a snow shelter keep you?"

Several young scientists set out on an investigation. They built a snow shelter and camped in it overnight. They positioned one Vernier Temperature Probe inside the shelter and put the other outside. They collected data using a Vernier LabPro and a TI graphing calculator, and set the sampling rate to one sample per hour from each probe. They found that inside the shelter, the temperature remained constant at 32°F. Spikes in the data indicated where investigators lit candles for light. Once the candles were extinguished, the temperature returned to 32°F. Outside the shelter the temperature dropped below 32°F, and then began to climb after daybreak.

Do Prairie Dogs Communicate through Barking Patterns?

Prairie dogs’ major predators include badgers, coyotes, bobcats, and golden eagles. It is commonly thought that prairie dogs bark to warn one another of impending danger. But can a pattern be distinguished?

Prairie dogs were stimulated by different threats and recorded on a video camera with a microphone. The videos were played back and the barks recorded in Logger Pro software using a Vernier Microphone and a LabPro. Students found that barks from different threats contained different peak frequencies.

Bark from badger threat (major peaks at 2200, 3500, and 4300 Hz)

The blacktailed prairie dog also has a display called the Jump-Yip, which involves throwing the forepaws into the air, pointing the nose straight up, and emitting an abrupt two-part vocalization. The Jump-Yip seems to mean "All’s well over here. I’m going to enjoy this carrot now." During this display, the major peaks occurred between 3000-4000 Hz.

Bark from coyote threat (major peaks at 2000, 2800, and 4000 Hz)

Jump-yip (major peaks clustered between 3000-4000 Hz)

Every single bark sound wave was different! An FFT of the sound reveals which primary sound frequency peaks make up the composite sound. Students concluded that human hearing can’t easily distinguish prairie dog barks. However, these barks are signals that may contain important information.

Dragonflytv can be seen on your local PBS station. For more information on these and other episodes visit their web site at http://pbskids.org/ dragonflytv.