DIY versus Professional: Weather Instruments Face off in an Inquiry Designed to Compare Their Accuracy

Article excerpt

[ILLUSTRATION OMITTED]

Weather, with its built-in atmospheric laboratory, is a natural source of inquiry. The ever-changing nature of weather provides a constant source of questions to investigate and connects to a multitude of physical science concepts. The question, "How accurate are homemade weather instruments in measuring air pressure, rainfall, wind speed, and wind direction?" led fourth- and fifth-grade students to collect and record data, to compare and contrast their data with local weather data, to learn the fundamentals of how weather instruments work, and to form conclusions about weather and climate.

[ILLUSTRATION OMITTED]

Weather Walk

To get students interested in weather and sharpen their observation skills, we took them on a weather walk. If possible, choose a day with a combination of weather conditions (e.g., sunny, windy, and rainy). We provided tools to help students in their observations: thermometers, notepads, colored pencils, bags for collecting, and a list of things to observe and sketch:

1. Portion of the sky covered by clouds

2. Type of clouds: puffy, flat, strands, semitransparent, dense, layered

3. Temperature in sunlight and shade

4. Trees budding

5. Leaves falling or changing color

6. Type of clothing people are wearing

Once back inside, students shared their observations. Observations included the wind blowing, the sidewalk was damp but it was not raining, bare trees, and overcast skies. Students made connections between what they observed and weather. They discussed how colder temperatures and shorter days triggered most of these events. A bulletin board in the classroom displayed weather events along with questions generated by the students (Figure 1, p. 54). After the initial observations, students learned that next they would build their own instruments for measuring weather.

Build Weather Stations

Scientists use highly specialized instruments to measure the weather, but it is also possible to build weather instruments at home or school. An internet search will result in several websites that provide directions for building weather instruments. Online, we have posted directions for building a weather station that includes a barometer, rain gauge, hygrometer, and anemometer (see NSTA Connection). The barometer will not give actual air pressure readings but will indicate whether the air pressure is rising or falling. The hygrometer will indicate an increase or decrease in humidity. Directions for two different types of anemometers are also included.

These anemometers both measure wind speed but are different from one another. One anemometer uses a Ping-Pong ball on a string connected to a protractor. The other anemometer is made of cups mounted on a dowel and connected to a motor. The motor becomes a generator when the wind spins the cups. Students can then read the voltage produced on a volt ohm meter. The voltage is related to wind speed based on prior calibrations of the anemometer. Students worked in small groups to build a set of instruments for their group's station. Our fourth-grade students were successful in building all of the instruments. Total time required to build all of the instruments was less than two hours.

Building weather instruments is an important piece of this lesson because it helps students understand the concepts behind each instrument and the weather condition it measures. Concepts related to the structure and function of the instruments were discussed both during the building process and during the data-collection process. William C. Robertson's book Stop Faking It! Air, Water, and Weather (2005) is a good resource for teachers who wish to increase their understanding of weather.

Daily Weather Readings

After the weather instruments were built, students needed some time to practice taking weather readings. …