Science Scope : Science Sampler

1/23/2006 - Annette Ricks Leitze, Melissa A. Mitchell, Nancy A. Melser, and Margo J. Byerly

Weather has been in the headlines recently, but for students to truly understand the science behind the phenomena, they should be familiar with such physical science concepts as the movement of molecules in solids, liquids, and gases; the relationship between temperature and pressure; and the transfer of energy into and out of a system. The following activities can be used to introduce these concepts using handmade devices.

Heating and cooling

Because changes in weather are often caused by changes in temperature, finding out how thermometers work can be a good place to begin a weather investigation. While store-bought thermometers measure temperature in precise units, degrees Celsius or Fahrenheit, simple homemade thermometers can be constructed to measure relative heat on a scale from 1 to 10.

To make the thermometers, students fill eight-ounce clear plastic bottles (screw caps removed) with water and a few drops of red food coloring. Place a clear plastic straw into each bottle’s mouth, about halfway into the liquid. Hold the straw upright and wedge a plug of nonhardening modeling clay into the opening around the straw. Press the clay into the neck of the bottle until the water rises in the straw midway between the top of the bottle and the top of the straw. On rectangular pieces of cardboard (about the same length as the straw above the bottle) draw 10 equally spaced horizontal lines about one centimeter apart to form a scale for the thermometer. Label the lines from 1 to 10, with 1 at the bottom and 10 at the top. Attach the cardboard scale to the straw with tape. When the room becomes warmer the water will also get warmer, expand, and rise higher in the straw, showing an increased “temperature” on the scale. Before using the thermometers, set them aside for several hours to allow for adjustment of the water level to ambient temperature, which will give more consistent readings.

Testing the thermometers under a variety of conditions will guide students to an understanding of how warming and cooling patterns occur around the globe. Have students explore these ideas by taking their thermometers home over the weekend and recording the temperature in a variety of locations and at a variety of times throughout the day and evening. Ask students to predict what time of day/night they think will be the hottest and the coolest. What other factors, aside from air temperature, might affect a particular reading?

The following activity demonstrates how different terrains affect warming and cooling patterns in different geographical regions. Air is warmed to some extent by the direct rays of the Sun, but air molecules are very poor conductors. Instead, our atmosphere is warmed largely by heat energy that has first been absorbed by the Earth itself and then reradiated into the surrounding air. Because landmasses are better absorbers of heat than are bodies of water, the air above beaches is warmer than the air above oceans. By the same token, landmasses cool more quickly than do bodies of water.

To help students investigate the phenomenon of unequal heating and cooling, challenge them to create miniature geographical regions of the world in five matching wide-mouth glass jars. Fill one jar with salt water, one with plain water, one with sand, one with soil and grass, and the last with rocks to represent, respectively, oceans, lakes, deserts, prairies, and mountains. Insert a store-bought thermometer into the top of each jar.

For a class of 30, divide students into five groups of six. Have each group make two of the same mini-region jars. That way, one of the two jars each group makes can be placed in the shade and one can be placed in the sun. Leave one complete set of jars in a shady place and one complete set of jars in a sunny place outside for at least 30 minutes. Each group takes readings for their own two jars and then the data is recorded on a whole-class table (either on the board or overhead) so that differences across jars/mini-regions can be observed.

To extend the lesson and increase the number of data points observed, have each successive class of 30 students add to the data table by reversing the locations of the two sets of jars. Jars in sunny spots are moved to the shade; jars in the shade are moved to the sun. At the end of 30 minutes, have the new class record the new temperatures. Have the temperatures changed from the previous readings? Predict which jars will cool or heat the fastest when moved back to their original locations. On the following day, be sure to have each class review the completed table in its entirety to observe the additional data. Which jars (geographic regions) seemed to hold their heat the longest? Which jars (geographic regions) seemed to cool the quickest?

Uneven heating across geographic regions causes air masses above the Earth to move (warm, “light” air rises; cool, “dense” air falls). This constant movement of air around the globe is what we call wind. The greater the pressure and temperature differences between two air masses, the stronger the wind will be! But, while unequal heating and cooling of land and water cause air to move, moving air also causes changes in temperature. Ask students what they do to cool down on a hot, steamy day. Chances are many will say “use a fan.” Does moving air have a cooling effect? Is the cooling effect enhanced when the moving air is also wet? How could we find out?

Air pressure

Air moves from areas of high pressure to areas of low pressure. In a low-pressure area, warm air rises and cools as it increases elevation. In a high-pressure area, cool air sinks, becoming warmer. Increasing air pressure produces clear skies and fair weather, while decreasing air pressure produces clouds and rain.

An activity to explore changes in air pressure can be carried out by constructing simple barometers. Cut the neck and shoulders (about the first 15 cm) off the top of a 1 liter clear plastic bottle. Discard the top. Fill the cylinder that remains with red-colored water to a depth of about 7.5 centimeters. Remove the screw cap from a second 1 liter clear plastic bottle and invert it into the half-cylinder of red water. The two bottles should fit snugly and remain upright, but not be completely airtight. The red water in the cylinder should now have risen about 2.5 centimeters into the neck of the inverted bottle. After allowing the bottles to remain undisturbed for about 15 minutes, mark the level of the water in the bottle by drawing a line on the outside of the cylinder with a black permanent marker. Add three more marks, each one centimeter apart, above the lowest mark. The lowest mark will indicate low air pressure; the highest mark will indicate high air pressure.

You must construct these barometers when it is raining or snowing because they must be “calibrated” at the absolutely lowest pressure. Because local weather dictates when the barometers can be built and calibrated, the teacher will likely need to prepare these ahead of time and the instruments stored for a few days or weeks before use. Be sure to keep the barometers in an area of the classroom where temperature fluctuations and air drafts can be best controlled. If water evaporates between construction and use, gently lift the inverted bottle from the cylinder and add water (a little at a time) until it again reaches the lowest of the three marks on the side of the reinserted inverted bottle.

Because it will be necessary to take multiple barometric readings in a single day, a class data table can again be utilized. Simultaneously send students outside to observe and record air temperature and cloud cover. Is there a relationship between air pressure and general weather conditions? What kind of air pressure (high or low) is generally associated with a storm? Would the pressure be rising or falling if a storm was beginning to clear? Each successive class of 30 students will record a new set of readings during their class period and the completed table shared across all classes on the following day.

Using bar graphs, line graphs, and circle graphs, students can organize and analyze data collected from the science activities. Discuss temperature fluctuations and how the graphs show that information at a quick glance. Further build on this idea by having students cut from their local newspaper the daily weather report showing the high and low temperatures recorded for the previous day. Collect several days (preferably more than one week) of data and have students create double bar graphs of high and low temperatures. Have students compare the graphs drawn from newspaper reports with graphs drawn from their own data collection for the same days.

After students have constructed and calibrated their barometers ask them to assemble the data from readings taken at the same hour of the day over a week or more. Have students use a frequency chart to record the daily barometer readings as high pressure, low pressure, or “in between.” Use the data from the frequency chart to create a circle graph. Which kind of pressure occurred most frequently? Most infrequently? How does the graph help you quickly answer these questions?

Annette Ricks Leitze (aleitze@bsu.edu) is a professor in the Department of Mathematical Sciences, Melissa A. Mitchell is a professor in the Department of Biology, and Nancy A. Melser is an assistant professor in the Department of Elementary Education at Ball State University in Muncie, Indiana. Margo J. Byerly is an assistant professor of Curriculum and Instruction at Western Illinois University in Macomb, Illinois.

Weather activity resources

Books

Bosak, S.V. 1991. Science is . . . a source book of interesting facts, projects and activities. Ontario, Canada: Scholastic Canada.
Carin, A.A. 1997. Teaching science through discovery (8th ed.). Columbus, OH: Merrill.
Lorbeer, G.C., and L.W. Nelson. 1992. Science activities for children. Dubuque, IA: Wm. C. Brown.
Taylor, B. 1993. Young discoverers: Weather and climate. New York: Kingfisher.

Websites

Wonderful World of Weather—
www.k12science.org/curriculum/weatherproj/
National Severe Storms Laboratory—
www.nssl.noaa.gov
Weather Here and There—
www.ncsa.uiuc.edu/edu/RSE/RSEred/WeatherHome.html
The Martian Sun-Times—
www.ucls.uchicago.edu/students/projects/martiansuntimes/
Live Weather Images—
www.weatherimages.org/
Weather for Kids—
www.srh.noaa.gov/tulsa/weather_kids.html
NOAA for Kids—
www.nws.noaa.gov/om/reachout/kidspage.shtml