By Amy Doeun
Chisago County 4-H has hosted a four-part STEM (science technology, engineering and math) workshop on water at the North Branch public library.
Angela Tevitt and Bobbie Harrington jointly teach the class. Tevit said the summer reading program at the library is STEM based. 4-H has been developing STEM programming for several years.
“I just love when it all comes together,” Tevit said.
On July 27, the topic was the water system. Tevit and Harrington explained that water is constantly moving throughout the world. Surface water re-enters the atmosphere through evaporation. Once it is in the atmosphere, it gathers in clouds.
“Clouds are made out of condensation,” Tevit said. “If we have enough condensation, we get precipitation. In addition to rain, other kinds of precipitation include snow, hail, sleet, mist and fog. It (precipitation) is any way for the water to come out of the sky and back down to the earth,” said Tevit.
Once water returns to surface, it runs into area lakes or rivers or is absorbed back into the ground. Plants absorb water from the ground and in turn return it to the atmosphere through transpiration.
“Transpiration is like perspiration,” Tevit explained. “Just like we sweat through our skin, the plants and leaves sweat.”
Harrington said about 10 percent of the planet’s humidity comes from transpiration.
The water in the ground can also return to the surface through percolation.
Harrington asked the crowd present for the presentations: “Have you ever been at Wild River State Park and you step off the trail and your feet get all muddy but it hasn’t rained? The water percolates up from the ground. This happens in places like a bog or swamp.”
Dew is a combination of evaporation and condensation.
Students created their own model of the water system by mapping it out on a plastic bag, placing a small amount of water in the bag and placing it in the sun, allowing solar power to begin the process of evaporation followed by condensation.
Finally, the students had some hands-on learning. Using a hill and a blue rope laid in a twisting pattern to represent a river, the children used live action to learn more about the water system. Some students acted as vegetation and others as rain drops. The raindrops traveled down the river but were caught by the vegetation; after circling the “vegetation,” the “water droplets” continued down the river.
“It looks like a crazy, chaotic game of tag, but hopefully they are learning something,” Tevit said.
As the children returned to their models that had been heating up in the sunshine, one excitedly exclaimed, “Look at my evaporation; oh, and here is my condensation!”