Should You Use Inquiry and Problem Solving Laboratories?

Janet Lanza
University of Arkansas at Little Rock

Testing the effect of surface area/volume ratios on heat loss.

Using plastic eggs, students constructed two sizes of "penguins", filled them with warm water, placed them on a bed of ice, and measured the drop in temperature. They conducted five replicates and discovered that the large "penguin" lost heat more slowly than did the small "penguin." Note that decorating the eggs to look like penguins isn’t necessary for the experiment, however, students often like doing this and, as long as it doesn’t consume too much time, I let them go.

Testing the effect of elephant ears as heat radiators.

This group of students knew that elephants radiate excess heat from their ears and they wanted to test this idea. They made “endothermic elephants” by burying a flashlight bulb in children’s modeling compound, attaching the bulb to a battery, and threading copper wire through the body with protrusions to look like the outside of ears. On five of ten replicates, they covered the wire with aluminum foil; these were "eared elephants," as compared to "earless elephants." Next, they measured the body temperature of the two groups. The differences in body temperature were as they had predicted—the “eared elephants” were cooler than the “earless elephants.”

Testing the effect of blubber’s insulative value.

This group of students wanted to test how effective "blubber" is in maintaining the body heat of mammals such as whales. They filled ten plastic eggs with warm water, covered half with vegetable shortening ("blubber"), then covered all with cellophane (to reduce the mess). Next, students placed the eggs on a bed of ice and measured the temperature of each for ten minutes. The temperature of the models with “blubber” decreased more slowly than the "blubberless" models—mimicking the insulative value of the blubber.