KINDERGARTEN - heating and cooling
Comparing how substances heat up.
· Taking temperature of different substances
Water most probably originated on this planet as gases emitted from volcanoes. The Earth's atmosphere captured this water and has continuously recycled it throughout time, in what is called the water cycle. Water evaporates and forms clouds. The clouds provide rain and snow, which is collected in rivers, lakes, underground reservoirs, and oceans that are the source for further evaporation. Heat from the Sun helps fuel the water cycle. In this lesson the students will learn that different substances heat up differently.
Under the same solar radiation (temperature), different substances will heat up differently. Oceans heat up slowly, but cool very slowly. Land heats up quickly, but then cools quickly. This causes a difference in air pressure which in turn causes wind. Breezes can be caused by conditions created by this changing heat.
Air that is warmed exerts less pressure on the ground causing a low pressure region. Air that is cooled is denser, causing a high pressure region. Remember that cold, cool, warm, and hot are relative terms. The movement of air is greatest from high pressure to low pressure when the temperature differential is the greatest.
The lab exercise is to prove to students that certain substances will heat up more quickly than others. In your discussion you might want to review that heat makes molecules of a substance move faster. Students should work in groups. Ideally in groups of two or 3 but it depends on how many lamps you have. Each group will have a lamp and a tray of white sand and a tray of black sand. There should be enough sand in each tray to cover the base of the thermometer as it rests in the dish.
There are various ways to heat the sand depending on your materials:
· Desk lamps with at least a 75 watt bulb work well. The lamp bulb just needs to be adjusted to be close to the sand.
· Heat lamps work but be sure to keep an eye on the temperature. Some heat lamps are so effective they reach the maximum for the thermometer very quickly and have even broken the thermometers. They also can burn students if they touch them. Heat lamps work best as a demo if you are short on lamps.
· You can also use sunlight but that takes more time. If you are short on time, you may want to prepare a set that is outside already for 10 minutes.
Tell students you are doing
an experiment to see if there is a difference in how quickly white sand
and black sand heat up or do they heat up the same.
Each group should have two
thermometers, one for the black sand and one for the white sand.
Students should read the starting temperature of each thermometer
before placing it in the sand dishes.
(NOTE: check when you
hand them out that the temperatures are about the same.
Some of the thermometers can be a few degrees off.) They should
write down the start temperature in the space on the worksheet.).
Students should then place a thermometer into black sand, and white
sand. Emphasize with students that each thermometer should be the
same distance below the surface.
Students should place their
tray in the sunlight or under a lamp for 10 minutes and then record the
temperature in the worksheet for heated white and black sand (you can also
create a data chart on the board and have the students provide their
Bring the trays inside (or
turn off the heat lamp) and let them cool for 10 minutes before students
record the temperatures.
While you are waiting,
either read or sing the song Drippy the Hippie to help students
learn the words precipitation, evaporation, and condensation. Using
the worksheet, discuss with children how water becomes clouds by
evaporation. Water can be recycled in the process.
6. Discuss with students their results. Which color sand heated faster? Which one cooled the quickest? The slowest? What color car do they think would get hotter faster, a black car or a white car?
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